diff --git a/.github/sync-repo-settings.yaml b/.github/sync-repo-settings.yaml
index fa2795c8f..5f9e868b3 100644
--- a/.github/sync-repo-settings.yaml
+++ b/.github/sync-repo-settings.yaml
@@ -11,9 +11,9 @@ branchProtectionRules:
       - docs
       - lint-gax
       - lint-tools
-      - test-gax (14)
+      - test-gax (18)
       - test-gax (16)
-      - test-tools (14)
+      - test-tools (18)
       - test-tools (16)
       - cla/google
       - windows-gax
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index c686ad3bd..acb365ab3 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [14, 16]
+        node: [18, 20]
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
@@ -30,7 +30,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [14, 16]
+        node: [18, 16]
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
@@ -51,7 +51,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [14, 16]
+        node: [18, 20]
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
@@ -72,7 +72,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [14, 16]
+        node: [18, 20]
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
@@ -95,7 +95,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 14
+          node-version: 18
       - run: cd gax; npm install
       - run: cd gax; npm test
         env:
@@ -106,7 +106,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 14
+          node-version: 18
       - run: cd tools; npm install
       - run: cd tools; npm test
         env:
@@ -117,7 +117,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 14
+          node-version: 18
       - run: cd logging-utils; npm install
       - run: cd logging-utils; npm test
         env:
@@ -128,7 +128,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 14
+          node-version: 18
       - run: cd gax; npm install
       - run: cd gax; npm run lint
   lint-tools:
@@ -137,7 +137,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 14
+          node-version: 18
       - run: cd tools; npm install
       - run: cd tools; npm run lint
   lint-logging-utils:
@@ -146,7 +146,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 14
+          node-version: 18
       - run: cd logging-utils; npm install
       - run: cd logging-utils; npm run lint
   docs:
@@ -155,7 +155,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 14
+          node-version: 18
       - run: cd gax; npm install
       - run: cd gax; npm run docs
       - uses: JustinBeckwith/linkinator-action@v1
diff --git a/.kokoro/common.cfg b/.kokoro/common.cfg
index bda58c77b..a205e8ffe 100644
--- a/.kokoro/common.cfg
+++ b/.kokoro/common.cfg
@@ -16,7 +16,7 @@ build_file: "gax-nodejs/.kokoro/trampoline_v2.sh"
 # Configure the docker image for kokoro-trampoline.
 env_vars: {
     key: "TRAMPOLINE_IMAGE"
-    value: "gcr.io/cloud-devrel-kokoro-resources/node:14-user"
+    value: "gcr.io/cloud-devrel-kokoro-resources/node:18-user"
 }
 env_vars: {
     key: "TRAMPOLINE_BUILD_FILE"
diff --git a/.kokoro/continuous/node14/common.cfg b/.kokoro/continuous/node14/common.cfg
deleted file mode 100644
index bda58c77b..000000000
--- a/.kokoro/continuous/node14/common.cfg
+++ /dev/null
@@ -1,24 +0,0 @@
-# Format: //devtools/kokoro/config/proto/build.proto
-
-# Build logs will be here
-action {
-  define_artifacts {
-    regex: "**/*sponge_log.xml"
-  }
-}
-
-# Download trampoline resources.
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
-
-# Use the trampoline script to run in docker.
-build_file: "gax-nodejs/.kokoro/trampoline_v2.sh"
-
-# Configure the docker image for kokoro-trampoline.
-env_vars: {
-    key: "TRAMPOLINE_IMAGE"
-    value: "gcr.io/cloud-devrel-kokoro-resources/node:14-user"
-}
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/gax-nodejs/.kokoro/test.sh"
-}
diff --git a/.kokoro/continuous/node14/lint.cfg b/.kokoro/continuous/node14/lint.cfg
deleted file mode 100644
index 018ec7aa0..000000000
--- a/.kokoro/continuous/node14/lint.cfg
+++ /dev/null
@@ -1,4 +0,0 @@
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/gax-nodejs/.kokoro/lint.sh"
-}
diff --git a/.kokoro/continuous/node14/samples-test.cfg b/.kokoro/continuous/node14/samples-test.cfg
deleted file mode 100644
index 3fb9c46ca..000000000
--- a/.kokoro/continuous/node14/samples-test.cfg
+++ /dev/null
@@ -1,12 +0,0 @@
-# Download resources for system tests (service account key, etc.)
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/google-cloud-nodejs"
-
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/gax-nodejs/.kokoro/samples-test.sh"
-}
-
-env_vars: {
-  key: "SECRET_MANAGER_KEYS"
-  value: "long-door-651-kokoro-system-test-service-account"
-}
\ No newline at end of file
diff --git a/.kokoro/continuous/node14/system-test.cfg b/.kokoro/continuous/node14/system-test.cfg
deleted file mode 100644
index 8a980142a..000000000
--- a/.kokoro/continuous/node14/system-test.cfg
+++ /dev/null
@@ -1,12 +0,0 @@
-# Download resources for system tests (service account key, etc.)
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/google-cloud-nodejs"
-
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/gax-nodejs/.kokoro/system-test.sh"
-}
-
-env_vars: {
-  key: "SECRET_MANAGER_KEYS"
-  value: "long-door-651-kokoro-system-test-service-account"
-}
\ No newline at end of file
diff --git a/.kokoro/continuous/node14/test.cfg b/.kokoro/continuous/node14/test.cfg
deleted file mode 100644
index e69de29bb..000000000
diff --git a/.kokoro/presubmit/node14/common.cfg b/.kokoro/presubmit/node14/common.cfg
deleted file mode 100644
index bda58c77b..000000000
--- a/.kokoro/presubmit/node14/common.cfg
+++ /dev/null
@@ -1,24 +0,0 @@
-# Format: //devtools/kokoro/config/proto/build.proto
-
-# Build logs will be here
-action {
-  define_artifacts {
-    regex: "**/*sponge_log.xml"
-  }
-}
-
-# Download trampoline resources.
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
-
-# Use the trampoline script to run in docker.
-build_file: "gax-nodejs/.kokoro/trampoline_v2.sh"
-
-# Configure the docker image for kokoro-trampoline.
-env_vars: {
-    key: "TRAMPOLINE_IMAGE"
-    value: "gcr.io/cloud-devrel-kokoro-resources/node:14-user"
-}
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/gax-nodejs/.kokoro/test.sh"
-}
diff --git a/.kokoro/presubmit/node14/samples-test.cfg b/.kokoro/presubmit/node14/samples-test.cfg
deleted file mode 100644
index 3fb9c46ca..000000000
--- a/.kokoro/presubmit/node14/samples-test.cfg
+++ /dev/null
@@ -1,12 +0,0 @@
-# Download resources for system tests (service account key, etc.)
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/google-cloud-nodejs"
-
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/gax-nodejs/.kokoro/samples-test.sh"
-}
-
-env_vars: {
-  key: "SECRET_MANAGER_KEYS"
-  value: "long-door-651-kokoro-system-test-service-account"
-}
\ No newline at end of file
diff --git a/.kokoro/presubmit/node14/system-test.cfg b/.kokoro/presubmit/node14/system-test.cfg
deleted file mode 100644
index 8a980142a..000000000
--- a/.kokoro/presubmit/node14/system-test.cfg
+++ /dev/null
@@ -1,12 +0,0 @@
-# Download resources for system tests (service account key, etc.)
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/google-cloud-nodejs"
-
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/gax-nodejs/.kokoro/system-test.sh"
-}
-
-env_vars: {
-  key: "SECRET_MANAGER_KEYS"
-  value: "long-door-651-kokoro-system-test-service-account"
-}
\ No newline at end of file
diff --git a/.kokoro/presubmit/node14/test.cfg b/.kokoro/presubmit/node14/test.cfg
deleted file mode 100644
index e69de29bb..000000000
diff --git a/.kokoro/release/docs.cfg b/.kokoro/release/docs.cfg
index e83e720e8..7256aba7a 100644
--- a/.kokoro/release/docs.cfg
+++ b/.kokoro/release/docs.cfg
@@ -11,7 +11,7 @@ before_action {
 # doc publications use a Python image.
 env_vars: {
     key: "TRAMPOLINE_IMAGE"
-    value: "gcr.io/cloud-devrel-kokoro-resources/node:14-user"
+    value: "gcr.io/cloud-devrel-kokoro-resources/node:18-user"
 }
 
 # Download trampoline resources.
diff --git a/.kokoro/release/publish.cfg b/.kokoro/release/publish.cfg
index 6e0e6efc9..f2b47538f 100644
--- a/.kokoro/release/publish.cfg
+++ b/.kokoro/release/publish.cfg
@@ -30,7 +30,7 @@ build_file: "gax-nodejs/.kokoro/trampoline_v2.sh"
 # Configure the docker image for kokoro-trampoline.
 env_vars: {
     key: "TRAMPOLINE_IMAGE"
-    value: "gcr.io/cloud-devrel-kokoro-resources/node:14-user"
+    value: "gcr.io/cloud-devrel-kokoro-resources/node:18-user"
 }
 
 env_vars: {
diff --git a/.kokoro/samples-test.sh b/.kokoro/samples-test.sh
index 8c5d108cb..c1cb0fc77 100755
--- a/.kokoro/samples-test.sh
+++ b/.kokoro/samples-test.sh
@@ -56,7 +56,7 @@ fi
 
 # codecov combines coverage across integration and unit tests. Include
 # the logic below for any environment you wish to collect coverage for:
-COVERAGE_NODE=14
+COVERAGE_NODE=18
 if npx check-node-version@3.3.0 --silent --node $COVERAGE_NODE; then
   NYC_BIN=./node_modules/nyc/bin/nyc.js
   if [ -f "$NYC_BIN" ]; then
diff --git a/.kokoro/system-test.sh b/.kokoro/system-test.sh
index 1f6a2f6ac..1a7df166e 100755
--- a/.kokoro/system-test.sh
+++ b/.kokoro/system-test.sh
@@ -51,7 +51,7 @@ npm run system-test
 
 # codecov combines coverage across integration and unit tests. Include
 # the logic below for any environment you wish to collect coverage for:
-COVERAGE_NODE=14
+COVERAGE_NODE=18
 if npx check-node-version@3.3.0 --silent --node $COVERAGE_NODE; then
   NYC_BIN=./node_modules/nyc/bin/nyc.js
   if [ -f "$NYC_BIN" ]; then
diff --git a/.kokoro/test.bat b/.kokoro/test.bat
index 0bb124052..baa52982b 100644
--- a/.kokoro/test.bat
+++ b/.kokoro/test.bat
@@ -21,7 +21,7 @@ cd ..
 @rem we upgrade Node.js in the image:
 SET PATH=%PATH%;/cygdrive/c/Program Files/nodejs/npm
 
-call nvm use v14.17.3
+call nvm use v18
 call which node
 
 call npm install || goto :error
diff --git a/.kokoro/test.sh b/.kokoro/test.sh
index 862d478d3..0d9f6392a 100755
--- a/.kokoro/test.sh
+++ b/.kokoro/test.sh
@@ -39,7 +39,7 @@ npm test
 
 # codecov combines coverage across integration and unit tests. Include
 # the logic below for any environment you wish to collect coverage for:
-COVERAGE_NODE=14
+COVERAGE_NODE=18
 if npx check-node-version@3.3.0 --silent --node $COVERAGE_NODE; then
   NYC_BIN=./node_modules/nyc/bin/nyc.js
   if [ -f "$NYC_BIN" ]; then
diff --git a/gax/.eslintignore b/gax/.eslintignore
index ea5b04aeb..07a7bd357 100644
--- a/gax/.eslintignore
+++ b/gax/.eslintignore
@@ -5,3 +5,7 @@ build/
 docs/
 protos/
 samples/generated/
+test/browser-test/
+test/showcase-echo-client/src/
+test/showcase-server/
+test/test-application/src/
\ No newline at end of file
diff --git a/gax/package.json b/gax/package.json
index dece0f0cd..014e25a12 100644
--- a/gax/package.json
+++ b/gax/package.json
@@ -10,61 +10,60 @@
     "!build/src/**/*.map"
   ],
   "dependencies": {
-    "@grpc/grpc-js": "^1.10.9",
+    "@grpc/grpc-js": "^1.12.6",
     "@grpc/proto-loader": "^0.7.13",
     "@types/long": "^5.0.0",
     "abort-controller": "^3.0.0",
-    "duplexify": "^4.0.0",
-    "google-auth-library": "^9.3.0",
-    "node-fetch": "^2.7.0",
+    "duplexify": "^4.1.3",
+    "google-auth-library": "^9.15.1",
+    "node-fetch": "^3.3.2",
     "object-hash": "^3.0.0",
-    "proto3-json-serializer": "^2.0.2",
-    "retry-request": "^7.0.0",
-    "uuid": "^9.0.1",
-    "protobufjs": "^7.3.2"
+    "proto3-json-serializer": "^3.0.0",
+    "protobufjs": "^7.4.0",
+    "retry-request": "^8.0.0"
   },
   "devDependencies": {
-    "@types/uuid": "^9.0.7",
     "@babel/plugin-proposal-private-methods": "^7.18.6",
-    "@types/mocha": "^9.0.0",
-    "@types/ncp": "^2.0.1",
+    "@types/mocha": "^10.0.10",
+    "@types/ncp": "^2.0.8",
     "@types/node": "^20.5.0",
-    "@types/node-fetch": "^2.6.11",
-    "@types/object-hash": "^3.0.0",
-    "@types/proxyquire": "^1.3.28",
-    "@types/pumpify": "^1.4.1",
-    "@types/sinon": "^17.0.0",
-    "@types/uglify-js": "^3.17.0",
-    "c8": "^9.0.0",
-    "cheerio": "1.0.0-rc.12",
-    "codecov": "^3.1.0",
+    "@types/node-fetch": "^2.6.12",
+    "@types/object-hash": "^3.0.6",
+    "@types/proxyquire": "^1.3.31",
+    "@types/pumpify": "^1.4.4",
+    "@types/sinon": "^17.0.3",
+    "@types/uglify-js": "^3.17.5",
+    "assert": "^2.1.0",
+    "c8": "^10.1.3",
+    "cheerio": "^1.0.0",
+    "codecov": "^3.8.3",
     "execa": "^5.0.0",
     "glob": "10.4.5",
     "google-proto-files": "^4.2.0",
-    "gts": "^5.0.0",
-    "jackspeak": "3.4.3",
-    "jsdoc": "^4.0.0",
+    "gts": "^6.0.2",
+    "jackspeak": "^3.0.2",
+    "jsdoc": "^4.0.4",
     "jsdoc-fresh": "^3.0.0",
     "jsdoc-region-tag": "^3.0.0",
-    "linkinator": "^4.0.0",
-    "lru-cache": "10.4.3",
-    "long": "^5.0.0",
-    "mkdirp": "^2.0.0",
-    "mocha": "^9.0.0",
+    "linkinator": "^6.1.2",
+    "long": "^5.2.4",
+    "lru-cache": "^10.0.0",
+    "mkdirp": "^3.0.1",
+    "mocha": "^11.1.0",
     "ncp": "^2.0.0",
-    "null-loader": "^4.0.0",
-    "pdfmake": "0.2.12",
-    "protobufjs-cli": "1.1.3",
-    "proxyquire": "^2.0.1",
-    "pumpify": "^2.0.0",
-    "sinon": "^18.0.0",
-    "stream-events": "^1.0.4",
+    "null-loader": "^4.0.1",
+    "pdfmake": "^0.2.18",
+    "protobufjs-cli": "^1.1.3",
+    "proxyquire": "^2.1.3",
+    "pumpify": "^2.0.1",
+    "sinon": "^19.0.2",
+    "stream-events": "^1.0.5",
     "ts-loader": "^8.0.0",
-    "typescript": "^5.1.6",
-    "uglify-js": "^3.17.0",
-    "walkdir": "^0.4.0",
-    "webpack": "^4.0.0",
-    "webpack-cli": "^4.0.0"
+    "typescript": "^5.7.3",
+    "uglify-js": "^3.19.3",
+    "walkdir": "^0.4.1",
+    "webpack": "^5.97.1",
+    "webpack-cli": "^6.0.1"
   },
   "scripts": {
     "docs": "jsdoc -c .jsdoc.js",
@@ -95,6 +94,12 @@
   "keywords": [
     "grpc"
   ],
+  "exports": {
+    ".": "./build/src/index.js",
+    "./fallback": "./build/src/fallback.js",
+    "./gax": "./build/src/gax.js",
+    "./build/src/protobuf": "./build/src/protobuf.js"
+  },
   "repository": {
     "type": "git",
     "url": "https://github.com/googleapis/gax-nodejs.git",
@@ -107,7 +112,7 @@
   },
   "homepage": "https://github.com/googleapis/gax-nodejs#readme",
   "engines": {
-    "node": ">=14"
+    "node": ">=18"
   },
   "browser": "build/src/fallback.js"
 }
diff --git a/gax/samples/package.json b/gax/samples/package.json
index fe458a230..525850957 100644
--- a/gax/samples/package.json
+++ b/gax/samples/package.json
@@ -3,7 +3,7 @@
   "license": "Apache-2.0",
   "author": "Google LLC",
   "engines": {
-    "node": ">=10"
+    "node": ">=18"
   },
   "repository": "googleapis/gax-nodejs",
   "private": true,
@@ -20,4 +20,4 @@
     "c8": "^9.0.0",
     "mocha": "^9.0.0"
   }
-}
+}
\ No newline at end of file
diff --git a/gax/samples/pagination.js b/gax/samples/pagination.js
index ad8ca6d97..a175bf34b 100644
--- a/gax/samples/pagination.js
+++ b/gax/samples/pagination.js
@@ -54,14 +54,14 @@ async function main() {
   const pageDescriptor = new gax.PageDescriptor(
     /* requestPageTokenField: */ 'pageToken',
     /* responsePageTokenField: */ 'nextPageToken',
-    /* resourceField: */ 'animals'
+    /* resourceField: */ 'animals',
   );
 
   // Create API call:
   const wrappedFunction = gax.createApiCall(
     /* func: */ doStuff,
     /* settings: */ settings,
-    /* descriptor: */ pageDescriptor
+    /* descriptor: */ pageDescriptor,
   );
 
   // Call it!
diff --git a/gax/samples/quickstart.js b/gax/samples/quickstart.js
index 35fc0bfd1..01463c8bb 100644
--- a/gax/samples/quickstart.js
+++ b/gax/samples/quickstart.js
@@ -45,7 +45,7 @@ async function main() {
   const settings = new gax.CallSettings();
   settings.retry = gax.createRetryOptions(
     /* retryCodes: */ [42],
-    /* backoffSettings: */ gax.createDefaultBackoffSettings()
+    /* backoffSettings: */ gax.createDefaultBackoffSettings(),
   );
 
   // and use createApiCall to get a promisifed function that handles retries!
diff --git a/gax/src/apiCaller.ts b/gax/src/apiCaller.ts
index 5c9590f1d..80857cb87 100644
--- a/gax/src/apiCaller.ts
+++ b/gax/src/apiCaller.ts
@@ -39,20 +39,20 @@ export interface APICaller {
     apiCall: SimpleCallbackFunction,
     argument: {},
     settings: {},
-    canceller: OngoingCallPromise | OngoingCall | StreamProxy
+    canceller: OngoingCallPromise | OngoingCall | StreamProxy,
   ): void;
   fail(
     canceller: OngoingCallPromise | OngoingCall | CancellableStream,
-    err: GoogleError
+    err: GoogleError,
   ): void;
   result(
-    canceller: OngoingCallPromise | OngoingCall | CancellableStream
+    canceller: OngoingCallPromise | OngoingCall | CancellableStream,
   ): CancellablePromise<ResultTuple> | CancellableStream;
 }
 
 export function createAPICaller(
   settings: CallSettings,
-  descriptor: Descriptor | undefined
+  descriptor: Descriptor | undefined,
 ): APICaller {
   if (!descriptor) {
     return new NormalApiCaller();
diff --git a/gax/src/apitypes.ts b/gax/src/apitypes.ts
index 8a6d49087..6004cc63a 100644
--- a/gax/src/apitypes.ts
+++ b/gax/src/apitypes.ts
@@ -59,7 +59,7 @@ export type APICallback = (
   err: GoogleError | null,
   response?: ResponseType,
   next?: NextPageRequestType,
-  rawResponse?: RawResponseType
+  rawResponse?: RawResponseType,
 ) => void;
 
 // The following five types mimic various gRPC calls (regular UnaryCall and
@@ -68,21 +68,21 @@ export type UnaryCall = (
   argument: {},
   metadata: {},
   options: {},
-  callback: APICallback
+  callback: APICallback,
 ) => GRPCCallResult;
 export type ServerStreamingCall = (
   argument: {},
   metadata: {},
-  options: {}
+  options: {},
 ) => Duplex & GRPCCallResult;
 export type ClientStreamingCall = (
   metadata: {},
   options: {},
-  callback?: APICallback
+  callback?: APICallback,
 ) => Duplex & GRPCCallResult;
 export type BiDiStreamingCall = (
   metadata: {},
-  options: {}
+  options: {},
 ) => Duplex & GRPCCallResult;
 export type GRPCCall =
   | UnaryCall
@@ -98,21 +98,21 @@ export interface GaxCallPromise {
   (
     argument: {},
     callOptions?: CallOptions,
-    callback?: APICallback
+    callback?: APICallback,
   ): CancellablePromise<ResultTuple>;
 }
 export interface GaxCallStream {
   (
     argument: {},
     callOptions?: CallOptions,
-    callback?: APICallback
+    callback?: APICallback,
   ): CancellableStream;
 }
 export interface GaxCall {
   (
     argument: {},
     callOptions?: CallOptions,
-    callback?: APICallback
+    callback?: APICallback,
   ): GaxCallResult;
 }
 export interface GRPCCallOtherArgs {
diff --git a/gax/src/bundlingCalls/bundleApiCaller.ts b/gax/src/bundlingCalls/bundleApiCaller.ts
index 78952a238..cb8c9097a 100644
--- a/gax/src/bundlingCalls/bundleApiCaller.ts
+++ b/gax/src/bundlingCalls/bundleApiCaller.ts
@@ -49,7 +49,7 @@ export class BundleApiCaller implements APICaller {
     apiCall: SimpleCallbackFunction,
     argument: {},
     settings: CallSettings,
-    status: OngoingCallPromise
+    status: OngoingCallPromise,
   ) {
     if (!settings.isBundling) {
       throw new GoogleError('Bundling enabled with no isBundling!');
diff --git a/gax/src/bundlingCalls/bundleDescriptor.ts b/gax/src/bundlingCalls/bundleDescriptor.ts
index cb6daad86..5765fe887 100644
--- a/gax/src/bundlingCalls/bundleDescriptor.ts
+++ b/gax/src/bundlingCalls/bundleDescriptor.ts
@@ -62,7 +62,7 @@ export class BundleDescriptor implements Descriptor {
     bundledField: string,
     requestDiscriminatorFields: string[],
     subresponseField: string | null,
-    byteLengthFunction: Function
+    byteLengthFunction: Function,
   ) {
     if (!byteLengthFunction && typeof subresponseField === 'function') {
       byteLengthFunction = subresponseField;
@@ -80,7 +80,7 @@ export class BundleDescriptor implements Descriptor {
       return new NormalApiCaller();
     }
     return new BundleApiCaller(
-      new BundleExecutor(settings.bundleOptions!, this)
+      new BundleExecutor(settings.bundleOptions!, this),
     );
   }
 }
diff --git a/gax/src/bundlingCalls/bundleExecutor.ts b/gax/src/bundlingCalls/bundleExecutor.ts
index 21f7ffdb3..61c8dbb8e 100644
--- a/gax/src/bundlingCalls/bundleExecutor.ts
+++ b/gax/src/bundlingCalls/bundleExecutor.ts
@@ -86,7 +86,7 @@ export class BundleExecutor {
    */
   constructor(
     bundleOptions: BundleOptions,
-    bundleDescriptor: BundleDescriptor
+    bundleDescriptor: BundleDescriptor,
   ) {
     this._options = bundleOptions;
     this._descriptor = bundleDescriptor;
@@ -107,11 +107,11 @@ export class BundleExecutor {
   schedule(
     apiCall: SimpleCallbackFunction,
     request: {[index: string]: Array<{}> | string},
-    callback?: TaskCallback
+    callback?: TaskCallback,
   ) {
     const bundleId = computeBundleId(
       request,
-      this._descriptor.requestDiscriminatorFields
+      this._descriptor.requestDiscriminatorFields,
     );
     callback = (callback || noop) as TaskCallback;
     if (bundleId === undefined) {
@@ -119,7 +119,7 @@ export class BundleExecutor {
         'bundling_schedule_bundleid_undefined',
         'The request does not have enough information for request bundling. ' +
           `Invoking immediately. Request: ${JSON.stringify(request)} ` +
-          `discriminator fields: ${this._descriptor.requestDiscriminatorFields}`
+          `discriminator fields: ${this._descriptor.requestDiscriminatorFields}`,
       );
       return apiCall(request, callback);
     }
@@ -127,7 +127,7 @@ export class BundleExecutor {
       warn(
         'bundling_no_bundled_field',
         `Request does not contain field ${this._descriptor.bundledField} that must present for bundling. ` +
-          `Invoking immediately. Request: ${JSON.stringify(request)}`
+          `Invoking immediately. Request: ${JSON.stringify(request)}`,
       );
       return apiCall(request, callback);
     }
@@ -137,7 +137,7 @@ export class BundleExecutor {
         apiCall,
         request,
         this._descriptor.bundledField,
-        this._descriptor.subresponseField
+        this._descriptor.subresponseField,
       );
     }
     let task = this._tasks[bundleId];
@@ -194,7 +194,7 @@ export class BundleExecutor {
         apiCall,
         request,
         this._descriptor.bundledField,
-        this._descriptor.subresponseField
+        this._descriptor.subresponseField,
       );
       task = this._tasks[bundleId];
     }
diff --git a/gax/src/bundlingCalls/bundlingUtils.ts b/gax/src/bundlingCalls/bundlingUtils.ts
index 20a04b029..e058f567e 100644
--- a/gax/src/bundlingCalls/bundlingUtils.ts
+++ b/gax/src/bundlingCalls/bundlingUtils.ts
@@ -33,7 +33,7 @@ import {RequestType} from '../apitypes';
  */
 export function computeBundleId(
   obj: RequestType,
-  discriminatorFields: string[]
+  discriminatorFields: string[],
 ) {
   const ids: unknown[] = [];
   let hasIds = false;
diff --git a/gax/src/bundlingCalls/task.ts b/gax/src/bundlingCalls/task.ts
index f4a72c583..c3dbafda9 100644
--- a/gax/src/bundlingCalls/task.ts
+++ b/gax/src/bundlingCalls/task.ts
@@ -54,7 +54,7 @@ export interface TaskCallback extends APICallback {
 export function deepCopyForResponse(
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   obj: any,
-  subresponseInfo: SubResponseInfo | null
+  subresponseInfo: SubResponseInfo | null,
 ) {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   let result: any;
@@ -91,7 +91,7 @@ export function deepCopyForResponse(
         // those subresponses are not shared among callbacks.
         result[key] = obj[key].slice(
           subresponseInfo.start,
-          subresponseInfo.end
+          subresponseInfo.end,
         );
       } else {
         result[key] = deepCopyForResponse(obj[key], null);
@@ -126,7 +126,7 @@ export class Task {
     apiCall: SimpleCallbackFunction,
     bundlingRequest: {},
     bundledField: string,
-    subresponseField?: string | null
+    subresponseField?: string | null,
   ) {
     this._apiCall = apiCall;
     this._request = bundlingRequest;
@@ -210,7 +210,7 @@ export class Task {
             self._data[i].callback(err, responses[i]);
           }
         }
-      }
+      },
     );
     return ids;
   }
diff --git a/gax/src/call.ts b/gax/src/call.ts
index b2fddacf0..8484e36d2 100644
--- a/gax/src/call.ts
+++ b/gax/src/call.ts
@@ -84,11 +84,11 @@ export class OngoingCall {
         err: GoogleError | null,
         response?: ResponseType,
         next?: NextPageRequestType,
-        rawResponse?: RawResponseType
+        rawResponse?: RawResponseType,
       ) => {
         this.completed = true;
         setImmediate(this.callback!, err, response, next, rawResponse);
-      }
+      },
     );
     if (canceller instanceof Promise) {
       canceller.catch(err => {
@@ -113,14 +113,14 @@ export class OngoingCallPromise extends OngoingCall {
    */
   constructor() {
     let resolveCallback: (
-      result: [ResponseType, NextPageRequestType, RawResponseType]
+      result: [ResponseType, NextPageRequestType, RawResponseType],
     ) => void;
     let rejectCallback: (err: Error) => void;
     const callback: APICallback = (
       err: GoogleError | null,
       response?: ResponseType,
       next?: NextPageRequestType,
-      rawResponse?: RawResponseType
+      rawResponse?: RawResponseType,
     ) => {
       if (err) {
         // If gRPC metadata exist, parsed google.rpc.status details.
diff --git a/gax/src/clientInterface.ts b/gax/src/clientInterface.ts
index 810892762..b9f3bd8b8 100644
--- a/gax/src/clientInterface.ts
+++ b/gax/src/clientInterface.ts
@@ -60,7 +60,7 @@ export interface Callback<
     err: Error | null | undefined,
     value?: ResponseObject | null,
     nextRequest?: NextRequestObject,
-    rawResponse?: RawResponseObject
+    rawResponse?: RawResponseObject,
   ): void;
 }
 
@@ -80,7 +80,7 @@ export interface PaginationCallback<
     err: Error | null,
     values?: ResponseType[],
     nextPageRequest?: RequestObject,
-    rawResponse?: ResponseObject
+    rawResponse?: ResponseObject,
   ): void;
 }
 
diff --git a/gax/src/createApiCall.ts b/gax/src/createApiCall.ts
index e36b98e4e..b3fdee987 100644
--- a/gax/src/createApiCall.ts
+++ b/gax/src/createApiCall.ts
@@ -58,7 +58,7 @@ export function createApiCall(
   settings: CallSettings,
   descriptor?: Descriptor,
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  _fallback?: boolean | 'proto' | 'rest' // unused here, used in fallback.ts implementation
+  _fallback?: boolean | 'proto' | 'rest', // unused here, used in fallback.ts implementation
 ): GaxCall {
   // we want to be able to accept both promise resolving to a function and a
   // function. Currently client librares are only calling this method with a
@@ -70,7 +70,7 @@ export function createApiCall(
   return (
     request: RequestType,
     callOptions?: CallOptions,
-    callback?: APICallback
+    callback?: APICallback,
   ) => {
     let currentApiCaller = apiCaller;
 
@@ -81,7 +81,7 @@ export function createApiCall(
       // If Gax streaming retries are enabled, check settings passed at call time and convert parameters if needed
       const convertedRetryOptions = convertRetryOptions(
         callOptions,
-        gaxStreamingRetries
+        gaxStreamingRetries,
       );
       thisSettings = settings.merge(convertedRetryOptions);
     } else {
@@ -109,7 +109,7 @@ export function createApiCall(
           if (retry.retryCodes.length > 0 && retry.shouldRetryFn) {
             warn(
               'either_retrycodes_or_shouldretryfn',
-              'Only one of retryCodes or shouldRetryFn may be defined. Ignoring retryCodes.'
+              'Only one of retryCodes or shouldRetryFn may be defined. Ignoring retryCodes.',
             );
             retry.retryCodes = [];
           }
@@ -119,19 +119,19 @@ export function createApiCall(
             retry.getResumptionRequestFn
           ) {
             throw new Error(
-              'getResumptionRequestFn can only be used when gaxStreamingRetries is set to true.'
+              'getResumptionRequestFn can only be used when gaxStreamingRetries is set to true.',
             );
           }
         }
         if (!streaming && retry) {
           if (retry.shouldRetryFn) {
             throw new Error(
-              'Using a function to determine retry eligibility is only supported with server streaming calls'
+              'Using a function to determine retry eligibility is only supported with server streaming calls',
             );
           }
           if (retry.getResumptionRequestFn) {
             throw new Error(
-              'Resumption strategy can only be used with server streaming retries'
+              'Resumption strategy can only be used with server streaming retries',
             );
           }
           if (retry.retryCodes && retry.retryCodes.length > 0) {
@@ -141,14 +141,14 @@ export function createApiCall(
               func,
               thisSettings.retry!,
               thisSettings.otherArgs as GRPCCallOtherArgs,
-              thisSettings.apiName
+              thisSettings.apiName,
             );
           }
         }
         return addTimeoutArg(
           func,
           thisSettings.timeout,
-          thisSettings.otherArgs as GRPCCallOtherArgs
+          thisSettings.otherArgs as GRPCCallOtherArgs,
         );
       })
       .then((apiCall: SimpleCallbackFunction) => {
diff --git a/gax/src/fallback.ts b/gax/src/fallback.ts
index 9e779f027..0d156c879 100644
--- a/gax/src/fallback.ts
+++ b/gax/src/fallback.ts
@@ -15,7 +15,7 @@
  */
 
 import {OutgoingHttpHeaders} from 'http';
-import * as objectHash from 'object-hash';
+import objectHash from 'object-hash';
 import * as protobuf from 'protobufjs';
 import * as gax from './gax';
 import * as routingHeader from './routingHeader';
@@ -126,13 +126,13 @@ export class GrpcClient {
        * A string is accepted for compatibility, all non-empty string values enable the HTTP REST fallback.
        */
       fallback?: boolean | string;
-    } = {}
+    } = {},
   ) {
     if (!isNodeJS()) {
       if (!options.auth) {
         throw new Error(
           JSON.stringify(options) +
-            'You need to pass auth instance to use gRPC-fallback client in browser or other non-Node.js environments. Use OAuth2Client from google-auth-library.'
+            'You need to pass auth instance to use gRPC-fallback client in browser or other non-Node.js environments. Use OAuth2Client from google-auth-library.',
         );
       }
       this.auth = options.auth as OAuth2Client;
@@ -196,7 +196,7 @@ export class GrpcClient {
     serviceName: string,
     clientConfig: gax.ClientConfig,
     configOverrides: gax.ClientConfig,
-    headers: OutgoingHttpHeaders
+    headers: OutgoingHttpHeaders,
   ) {
     function buildMetadata(abTests: {}, moreHeaders: OutgoingHttpHeaders) {
       const metadata: OutgoingHttpHeaders = {};
@@ -220,7 +220,7 @@ export class GrpcClient {
         )[0]
       ) {
         clientVersions.push(
-          ...(metadata[CLIENT_VERSION_HEADER] as string[])[0].split(' ')
+          ...(metadata[CLIENT_VERSION_HEADER] as string[])[0].split(' '),
         );
       }
       clientVersions.push(`grpc-web/${version}`);
@@ -244,7 +244,7 @@ export class GrpcClient {
                 ).push(...value);
               } else {
                 throw new Error(
-                  `Can not add value ${value} to the call metadata.`
+                  `Can not add value ${value} to the call metadata.`,
                 );
               }
             }
@@ -260,7 +260,7 @@ export class GrpcClient {
       clientConfig,
       configOverrides,
       Status,
-      {metadataBuilder: buildMetadata}
+      {metadataBuilder: buildMetadata},
     );
   }
 
@@ -280,7 +280,7 @@ export class GrpcClient {
     opts: ClientStubOptions,
     // For consistency with createStub in grpc.ts, customServicePath is defined:
     // eslint-disable-next-line @typescript-eslint/no-unused-vars
-    customServicePath?: boolean
+    customServicePath?: boolean,
   ) {
     if (!this.authClient) {
       if (this.auth && 'getClient' in this.auth) {
@@ -300,7 +300,7 @@ export class GrpcClient {
       if (universeFromAuth && opts.universeDomain !== universeFromAuth) {
         throw new Error(
           `The configured universe domain (${opts.universeDomain}) does not match the universe domain found in the credentials (${universeFromAuth}). ` +
-            "If you haven't configured the universe domain explicitly, googleapis.com is the default."
+            "If you haven't configured the universe domain explicitly, googleapis.com is the default.",
         );
       }
     }
@@ -319,7 +319,7 @@ export class GrpcClient {
     }
     if (!servicePath) {
       throw new Error(
-        `Cannot determine service API path for service ${service.name}.`
+        `Cannot determine service API path for service ${service.name}.`,
       );
     }
 
@@ -346,7 +346,7 @@ export class GrpcClient {
       encoder,
       decoder,
       this.numericEnums,
-      this.minifyJson
+      this.minifyJson,
     );
 
     return serviceStub;
@@ -411,7 +411,7 @@ export function createApiCall(
   settings: gax.CallSettings,
   descriptor?: Descriptor,
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  _fallback?: boolean | string // unused; for compatibility only
+  _fallback?: boolean | string, // unused; for compatibility only
 ): GaxCall {
   if (
     descriptor &&
@@ -420,14 +420,14 @@ export function createApiCall(
   ) {
     return () => {
       throw new Error(
-        'The REST transport currently does not support client-streaming or bidi-stream calls.'
+        'The REST transport currently does not support client-streaming or bidi-stream calls.',
       );
     };
   }
   if (descriptor && 'streaming' in descriptor && !isNodeJS()) {
     return () => {
       throw new Error(
-        'Server streaming over the REST transport is only supported in Node.js.'
+        'Server streaming over the REST transport is only supported in Node.js.',
       );
     };
   }
diff --git a/gax/src/fallbackRest.ts b/gax/src/fallbackRest.ts
index 87984f03e..b6e5f7621 100644
--- a/gax/src/fallbackRest.ts
+++ b/gax/src/fallbackRest.ts
@@ -29,7 +29,7 @@ export function encodeRequest(
   servicePort: number,
   request: {},
   numericEnums: boolean,
-  minifyJson: boolean
+  minifyJson: boolean,
 ): FetchParameters {
   const headers: {[key: string]: string} = {
     'Content-Type': 'application/json',
@@ -51,7 +51,7 @@ export function encodeRequest(
     throw new Error(
       `Cannot build HTTP request for ${JSON.stringify(json)}, method: ${
         rpc.name
-      }`
+      }`,
     );
   }
 
@@ -75,7 +75,7 @@ export function encodeRequest(
   const body = JSON.stringify(transcoded.data);
   const url = `${protocol}://${servicePath}:${servicePort}/${transcoded.url.replace(
     /^\//,
-    ''
+    '',
   )}?${transcoded.queryString}`;
 
   return {
@@ -89,7 +89,7 @@ export function encodeRequest(
 export function decodeResponse(
   rpc: protobuf.Method,
   ok: boolean,
-  response: Buffer | ArrayBuffer
+  response: Buffer | ArrayBuffer,
 ): {} {
   // eslint-disable-next-line n/no-unsupported-features/node-builtins
   const decodedString = new TextDecoder().decode(response);
@@ -104,7 +104,7 @@ export function decodeResponse(
   const message = serializer.fromProto3JSON(rpc.resolvedResponseType!, json);
   if (!message) {
     throw new Error(
-      `Received null or malformed response from JSON serializer from RPC ${rpc.name}`
+      `Received null or malformed response from JSON serializer from RPC ${rpc.name}`,
     );
   }
   return rpc.resolvedResponseType!.toObject(message, defaultToObjectOptions);
diff --git a/gax/src/fallbackServiceStub.ts b/gax/src/fallbackServiceStub.ts
index cf28522b8..4fcd1db58 100644
--- a/gax/src/fallbackServiceStub.ts
+++ b/gax/src/fallbackServiceStub.ts
@@ -17,17 +17,20 @@
 /* global window */
 /* global AbortController */
 
-import nodeFetch from 'node-fetch';
-import {Response as NodeFetchResponse, RequestInit} from 'node-fetch';
+import type {
+  Response as NodeFetchResponse,
+  RequestInit,
+} from 'node-fetch' with {'resolution-mode': 'import'};
 import {AbortController as NodeAbortController} from 'abort-controller';
-
+import type nodeFetch from 'node-fetch' with {'resolution-mode': 'import'};
 import {hasWindowFetch, hasAbortController, isNodeJS} from './featureDetection';
 import {AuthClient} from './fallback';
 import {StreamArrayParser} from './streamArrayParser';
 import {pipeline, PipelineSource} from 'stream';
 import type {Agent as HttpAgent} from 'http';
 import type {Agent as HttpsAgent} from 'https';
-
+const fetchNode = (...args: Parameters<typeof nodeFetch>) =>
+  import('node-fetch').then(({default: fetch}) => fetch(...args));
 interface NodeFetchType {
   (url: RequestInfo, init?: RequestInit): Promise<Response>;
 }
@@ -58,7 +61,7 @@ export interface FallbackServiceStub {
     request: {},
     options?: {},
     metadata?: {},
-    callback?: (err?: Error, response?: {} | undefined) => void
+    callback?: (err?: Error, response?: {} | undefined) => void,
   ) => StreamArrayParser | {cancel: () => void};
 }
 
@@ -84,19 +87,19 @@ export function generateServiceStub(
     servicePort: number,
     request: {},
     numericEnums: boolean,
-    minifyJson: boolean
+    minifyJson: boolean,
   ) => FetchParameters,
   responseDecoder: (
     rpc: protobuf.Method,
     ok: boolean,
-    response: Buffer | ArrayBuffer
+    response: Buffer | ArrayBuffer,
   ) => {},
   numericEnums: boolean,
-  minifyJson: boolean
+  minifyJson: boolean,
 ) {
   const fetch = hasWindowFetch()
     ? window.fetch
-    : (nodeFetch as unknown as NodeFetchType);
+    : (fetchNode as unknown as NodeFetchType);
 
   const serviceStub: FallbackServiceStub = {
     // close method should close all cancel controllers. If this feature request in the future, we can have a cancelControllerFactory that tracks created cancel controllers, and abort them all in close method.
@@ -109,7 +112,7 @@ export function generateServiceStub(
       request: {},
       options?: {[name: string]: string},
       _metadata?: {} | Function,
-      callback?: Function
+      callback?: Function,
     ) => {
       options ??= {};
 
@@ -125,7 +128,7 @@ export function generateServiceStub(
           servicePort,
           request,
           numericEnums,
-          minifyJson
+          minifyJson,
         );
       } catch (err) {
         // we could not encode parameters; pass error to the callback
@@ -158,11 +161,7 @@ export function generateServiceStub(
               ...authHeader,
               ...headers,
             },
-            body: fetchParameters.body as
-              | string
-              | Buffer
-              | Uint8Array
-              | undefined,
+            body: fetchParameters.body as string | Buffer | undefined,
             method: fetchParameters.method,
             signal: cancelSignal,
           };
@@ -193,7 +192,7 @@ export function generateServiceStub(
                   }
                   streamArrayParser.emit('error', err);
                 }
-              }
+              },
             );
             return;
           } else {
diff --git a/gax/src/gax.ts b/gax/src/gax.ts
index 64f381443..a38152c24 100644
--- a/gax/src/gax.ts
+++ b/gax/src/gax.ts
@@ -86,7 +86,7 @@ export class RetryOptions {
     retryCodes: number[],
     backoffSettings: BackoffSettings,
     shouldRetryFn?: (error: GoogleError) => boolean,
-    getResumptionRequestFn?: (request: RequestType) => RequestType
+    getResumptionRequestFn?: (request: RequestType) => RequestType,
   ) {
     this.retryCodes = retryCodes;
     this.backoffSettings = backoffSettings;
@@ -324,7 +324,7 @@ export class CallSettings {
  */
 export function convertRetryOptions(
   options?: CallOptions,
-  gaxStreamingRetries?: boolean
+  gaxStreamingRetries?: boolean,
 ): CallOptions | undefined {
   // options will be undefined if no CallOptions object is passed at call time
   if (!options) {
@@ -343,21 +343,21 @@ export function convertRetryOptions(
       warn(
         'retry_request_options',
         'objectMode override is not supported. It is set to true internally by default in gax.',
-        'UnsupportedParameterWarning'
+        'UnsupportedParameterWarning',
       );
     }
     if (options.retryRequestOptions.noResponseRetries !== undefined) {
       warn(
         'retry_request_options',
         'noResponseRetries override is not supported. Please specify retry codes or a function to determine retry eligibility.',
-        'UnsupportedParameterWarning'
+        'UnsupportedParameterWarning',
       );
     }
     if (options.retryRequestOptions.currentRetryAttempt !== undefined) {
       warn(
         'retry_request_options',
         'currentRetryAttempt override is not supported. Retry attempts are tracked internally.',
-        'UnsupportedParameterWarning'
+        'UnsupportedParameterWarning',
       );
     }
 
@@ -392,7 +392,7 @@ export function convertRetryOptions(
         warn(
           'retry_request_options_no_max_retries_timeout',
           'Neither maxRetries nor totalTimeout were passed. Defaulting to totalTimeout of 30000ms.',
-          'MissingParameterWarning'
+          'MissingParameterWarning',
         );
       }
     }
@@ -408,14 +408,14 @@ export function convertRetryOptions(
     const convertedRetryOptions = createRetryOptions(
       retryCodes,
       backoffSettings,
-      shouldRetryFn
+      shouldRetryFn,
     );
     options.retry = convertedRetryOptions;
     delete options.retryRequestOptions; // completely remove them to avoid any further confusion
     warn(
       'retry_request_options',
       'retryRequestOptions will be deprecated in a future release. Please use retryOptions to pass retry options at call time',
-      'DeprecationWarning'
+      'DeprecationWarning',
     );
   }
   return options;
@@ -436,7 +436,7 @@ export function createRetryOptions(
   retryCodes: number[],
   backoffSettings: BackoffSettings,
   shouldRetryFn?: (error: GoogleError) => boolean,
-  getResumptionRequestFn?: (request: RequestType) => RequestType
+  getResumptionRequestFn?: (request: RequestType) => RequestType,
 ): RetryOptions {
   return {
     retryCodes,
@@ -478,7 +478,7 @@ export function createBackoffSettings(
   initialRpcTimeoutMillis: number | null,
   rpcTimeoutMultiplier: number | null,
   maxRpcTimeoutMillis: number | null,
-  totalTimeoutMillis: number | null
+  totalTimeoutMillis: number | null,
 ): BackoffSettings {
   return {
     initialRetryDelayMillis,
@@ -527,7 +527,7 @@ export function createMaxRetriesBackoffSettings(
   initialRpcTimeoutMillis: number,
   rpcTimeoutMultiplier: number,
   maxRpcTimeoutMillis: number,
-  maxRetries: number
+  maxRetries: number,
 ): BackoffSettings {
   return {
     initialRetryDelayMillis,
@@ -607,7 +607,7 @@ function constructRetry(
   methodConfig: MethodConfig | null,
   retryCodes: {[index: string]: string[]} | undefined,
   retryParams: {[index: string]: {}} | undefined,
-  retryNames: {[index: string]: {}}
+  retryNames: {[index: string]: {}},
 ): RetryOptions | null | undefined {
   if (!methodConfig) {
     return null;
@@ -633,7 +633,7 @@ function constructRetry(
       params.initial_rpc_timeout_millis,
       params.rpc_timeout_multiplier,
       params.max_rpc_timeout_millis,
-      params.total_timeout_millis
+      params.total_timeout_millis,
     );
   }
   return createRetryOptions(codes!, backoffSettings!);
@@ -654,7 +654,7 @@ function constructRetry(
  */
 function mergeRetryOptions(
   retry: RetryOptions,
-  overrides: Partial<RetryOptions>
+  overrides: Partial<RetryOptions>,
 ): RetryOptions | null {
   if (!overrides) {
     return null;
@@ -686,7 +686,7 @@ function mergeRetryOptions(
     retryCodes!,
     backoffSettings!,
     shouldRetryFn!,
-    getResumptionRequestFn!
+    getResumptionRequestFn!,
   );
 }
 
@@ -790,7 +790,7 @@ export function constructSettings(
   clientConfig: ClientConfig,
   configOverrides: ClientConfig,
   retryNames: {},
-  otherArgs?: {}
+  otherArgs?: {},
 ) {
   otherArgs = otherArgs || {};
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -818,7 +818,7 @@ export function constructSettings(
       methodConfig,
       serviceConfig.retry_codes,
       serviceConfig.retry_params,
-      retryNames
+      retryNames,
     );
     let bundlingConfig = methodConfig!.bundling;
     let timeout = methodConfig!.timeout_millis;
@@ -838,8 +838,8 @@ export function constructSettings(
           overridingMethod,
           overrides.retry_codes,
           overrides.retry_params,
-          retryNames
-        )!
+          retryNames,
+        )!,
       );
     }
     const apiName = serviceName;
@@ -865,7 +865,7 @@ export function createByteLengthFunction(message: typeof Message) {
       const stringified = JSON.stringify(obj);
       warn(
         'error_encoding_protobufjs_object',
-        `Cannot encode protobuf.js object: ${stringified}: ${err}`
+        `Cannot encode protobuf.js object: ${stringified}: ${err}`,
       );
       // We failed to encode the object properly, let's just return an upper boundary of its length.
       // It's only needed for calculating the size of the batch, so it's safe if it's bigger than needed.
diff --git a/gax/src/googleError.ts b/gax/src/googleError.ts
index e9070b68f..e7305dbc4 100644
--- a/gax/src/googleError.ts
+++ b/gax/src/googleError.ts
@@ -38,7 +38,7 @@ export class GoogleError extends Error {
       if (err.metadata && err.metadata.get('grpc-status-details-bin')) {
         const statusDetailsObj: GRPCStatusDetailsObject =
           decoder.decodeGRPCStatusDetails(
-            err.metadata.get('grpc-status-details-bin') as []
+            err.metadata.get('grpc-status-details-bin') as [],
           );
         if (
           statusDetailsObj &&
@@ -88,7 +88,7 @@ export class GoogleError extends Error {
     const proto3Error = decoder.decodeHTTPError(json['error']);
     const error = Object.assign(
       new GoogleError(json['error']['message']),
-      proto3Error
+      proto3Error,
     );
     // Get gRPC Status Code
     if (
@@ -182,7 +182,7 @@ export class GoogleErrorDecoder {
     const match = anyValue.type_url.match(/^type.googleapis.com\/(.*)/);
     if (!match) {
       throw new Error(
-        `Unknown type encoded in google.protobuf.any: ${anyValue.type_url}`
+        `Unknown type encoded in google.protobuf.any: ${anyValue.type_url}`,
       );
     }
     const typeName = match[1];
@@ -239,14 +239,14 @@ export class GoogleErrorDecoder {
 
   // Decodes gRPC metadata error details which is an instance of google.rpc.Status.
   decodeGRPCStatusDetails(
-    bufferArr: Buffer[] | ArrayBuffer[]
+    bufferArr: Buffer[] | ArrayBuffer[],
   ): GRPCStatusDetailsObject {
     const details: protobuf.Message<{}>[] = [];
     let errorInfo;
     bufferArr.forEach(buffer => {
       const uint8array = new Uint8Array(buffer);
       const rpcStatus = this.statusType.decode(
-        uint8array
+        uint8array,
       ) as unknown as RpcStatus;
       for (const detail of rpcStatus.details) {
         try {
@@ -272,7 +272,7 @@ export class GoogleErrorDecoder {
     const errorMessage = serializer.fromProto3JSON(this.statusType, json);
     if (!errorMessage) {
       throw new Error(
-        `Received error message ${json}, but failed to serialize as proto3 message`
+        `Received error message ${json}, but failed to serialize as proto3 message`,
       );
     }
     return this.statusType.toObject(errorMessage, defaultToObjectOptions);
@@ -280,7 +280,7 @@ export class GoogleErrorDecoder {
 
   // Decodes http error details which is an instance of Array<google.protobuf.Any>.
   decodeHttpStatusDetails(
-    rawDetails: Array<ProtobufAny>
+    rawDetails: Array<ProtobufAny>,
   ): GRPCStatusDetailsObject {
     // eslint-disable-next-line @typescript-eslint/no-unused-vars
     const details: protobuf.Message<{}>[] = [];
diff --git a/gax/src/grpc.ts b/gax/src/grpc.ts
index ff8d06f67..37c9a693a 100644
--- a/gax/src/grpc.ts
+++ b/gax/src/grpc.ts
@@ -24,7 +24,7 @@ import {join} from 'path';
 import {OutgoingHttpHeaders} from 'http';
 import * as path from 'path';
 import * as protobuf from 'protobufjs';
-import * as objectHash from 'object-hash';
+import objectHash from 'object-hash';
 
 import * as gax from './gax';
 import {ClientOptions} from '@grpc/grpc-js/build/src/client';
@@ -37,11 +37,11 @@ INCLUDE_DIRS.push(googleProtoFilesDir);
 
 // COMMON_PROTO_FILES logic is here for protobufjs loads (see
 // GoogleProtoFilesRoot below)
-import * as commonProtoFiles from './protosList.json';
+import commonProtoFiles from './protosList.json';
 import {google} from '../protos/http';
 // use the correct path separator for the OS we are running on
 const COMMON_PROTO_FILES: string[] = commonProtoFiles.map(file =>
-  file.replace(/[/\\]/g, path.sep)
+  file.replace(/[/\\]/g, path.sep),
 );
 
 export interface GrpcClientOptions extends GoogleAuthOptions {
@@ -131,7 +131,7 @@ export class GrpcClient {
    */
   private static protoCacheKey(
     filename: string | string[],
-    options: grpcProtoLoader.Options
+    options: grpcProtoLoader.Options,
   ) {
     if (
       !filename ||
@@ -204,13 +204,13 @@ export class GrpcClient {
         ? grpc.credentials.createSsl(
             null,
             Buffer.from(opts.key),
-            Buffer.from(opts.cert)
+            Buffer.from(opts.cert),
           )
         : grpc.credentials.createSsl();
     const client = await this.auth.getClient();
     const credentials = grpc.credentials.combineChannelCredentials(
       sslCreds,
-      grpc.credentials.createFromGoogleCredential(client)
+      grpc.credentials.createFromGoogleCredential(client),
     );
     return credentials;
   }
@@ -243,7 +243,7 @@ export class GrpcClient {
   loadFromProto(
     filename: string | string[],
     options: grpcProtoLoader.Options,
-    ignoreCache = false
+    ignoreCache = false,
   ) {
     const cacheKey = GrpcClient.protoCacheKey(filename, options);
     let grpcPackage = cacheKey
@@ -275,7 +275,7 @@ export class GrpcClient {
   loadProto(
     protoPath: string,
     filename?: string | string[],
-    ignoreCache = false
+    ignoreCache = false,
   ) {
     if (!filename) {
       filename = path.basename(protoPath);
@@ -325,7 +325,7 @@ export class GrpcClient {
     }
     return function buildMetadata(
       abTests?: {},
-      moreHeaders?: OutgoingHttpHeaders
+      moreHeaders?: OutgoingHttpHeaders,
     ) {
       // TODO: bring the A/B testing info into the metadata.
       let copied = false;
@@ -365,14 +365,14 @@ export class GrpcClient {
     serviceName: string,
     clientConfig: gax.ClientConfig,
     configOverrides: gax.ClientConfig,
-    headers: OutgoingHttpHeaders
+    headers: OutgoingHttpHeaders,
   ) {
     return gax.constructSettings(
       serviceName,
       clientConfig,
       configOverrides,
       this.grpc.status,
-      {metadataBuilder: this.metadataBuilder(headers)}
+      {metadataBuilder: this.metadataBuilder(headers)},
     );
   }
 
@@ -392,7 +392,7 @@ export class GrpcClient {
   async createStub(
     CreateStub: typeof ClientStub,
     options: ClientStubOptions,
-    customServicePath?: boolean
+    customServicePath?: boolean,
   ) {
     // The following options are understood by grpc-gcp and need a special treatment
     // (should be passed without a `grpc.` prefix)
@@ -403,12 +403,12 @@ export class GrpcClient {
     ];
     const [cert, key] = await this._detectClientCertificate(
       options,
-      options.universeDomain
+      options.universeDomain,
     );
     const servicePath = this._mtlsServicePath(
       options.servicePath,
       customServicePath,
-      cert && key
+      cert && key,
     );
     const opts = Object.assign({}, options, {cert, key, servicePath});
     const serviceAddress = servicePath + ':' + opts.port;
@@ -420,7 +420,7 @@ export class GrpcClient {
       if (universeFromAuth && options.universeDomain !== universeFromAuth) {
         throw new Error(
           `The configured universe domain (${options.universeDomain}) does not match the universe domain found in the credentials (${universeFromAuth}). ` +
-            "If you haven't configured the universe domain explicitly, googleapis.com is the default."
+            "If you haven't configured the universe domain explicitly, googleapis.com is the default.",
         );
       }
     }
@@ -453,7 +453,7 @@ export class GrpcClient {
     const stub = new CreateStub(
       serviceAddress,
       creds,
-      grpcOptions as ClientOptions
+      grpcOptions as ClientOptions,
     );
     return stub;
   }
@@ -467,7 +467,7 @@ export class GrpcClient {
    */
   async _detectClientCertificate(
     opts?: ClientOptions,
-    universeDomain?: string
+    universeDomain?: string,
   ) {
     const certRegex =
       /(?<cert>-----BEGIN CERTIFICATE-----.*?-----END CERTIFICATE-----)/s;
@@ -480,7 +480,7 @@ export class GrpcClient {
     ) {
       if (universeDomain && universeDomain !== 'googleapis.com') {
         throw new Error(
-          'mTLS is not supported outside of googleapis.com universe domain.'
+          'mTLS is not supported outside of googleapis.com universe domain.',
         );
       }
       if (opts?.cert && opts?.key) {
@@ -491,7 +491,7 @@ export class GrpcClient {
       const metadataPath = join(
         os.homedir(),
         '.secureConnect',
-        'context_aware_metadata.json'
+        'context_aware_metadata.json',
       );
       const metadata = JSON.parse(await readFileAsync(metadataPath));
       if (!metadata.cert_provider_command) {
@@ -499,7 +499,7 @@ export class GrpcClient {
       }
       const stdout = await execFileAsync(
         metadata.cert_provider_command[0],
-        metadata.cert_provider_command.slice(1)
+        metadata.cert_provider_command.slice(1),
       );
       const matchCert = stdout.toString().match(certRegex);
       const matchKey = stdout.toString().match(keyRegex);
@@ -526,7 +526,7 @@ export class GrpcClient {
   _mtlsServicePath(
     servicePath: string | undefined,
     customServicePath: boolean | undefined,
-    hasCertificate: boolean
+    hasCertificate: boolean,
   ): string | undefined {
     // If user provides a custom service path, return the current service
     // path and do not attempt to add mtls subdomain:
diff --git a/gax/src/iamService.ts b/gax/src/iamService.ts
index 758536775..1ae5539ae 100644
--- a/gax/src/iamService.ts
+++ b/gax/src/iamService.ts
@@ -49,7 +49,7 @@ export class IamClient {
   constructor(
     gaxGrpc: GrpcClient | FallbackGrpcClient,
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    options: ClientOptions
+    options: ClientOptions,
   ) {
     this.gaxGrpc = gaxGrpc;
     // Ensure that options include the service address and port.
@@ -61,7 +61,7 @@ export class IamClient {
         apiEndpoint: options.apiEndpoint,
         fallback: options.fallback,
       },
-      options
+      options,
     ) as ClientOptions & ClientStubOptions;
     version = opts.fallback ? fallback.version : version;
     opts.scopes = (this.constructor as typeof IamClient).scopes;
@@ -90,7 +90,7 @@ export class IamClient {
       'google.iam.v1.IAMPolicy',
       gapicConfig as gax.ClientConfig,
       opts!.clientConfig || {},
-      {'x-goog-api-client': clientHeader.join(' ')}
+      {'x-goog-api-client': clientHeader.join(' ')},
     );
     this.innerApiCalls = {};
   }
@@ -117,7 +117,7 @@ export class IamClient {
       this._opts.fallback
         ? this._protos.lookupService('google.iam.v1.IAMPolicy')
         : this._protos.google.iam.v1.IAMPolicy,
-      this._opts
+      this._opts,
     ) as Promise<{[method: string]: Function}>;
     // Iterate over each of the methods that the service provides
     // and create an API call method for each.
@@ -139,12 +139,12 @@ export class IamClient {
           },
         (err: Error | null | undefined) => () => {
           throw err;
-        }
+        },
       );
       this.innerApiCalls[methodName] = createApiCall(
         innerCallPromise,
         this._defaults[methodName],
-        this.descriptors.page[methodName]
+        this.descriptors.page[methodName],
       );
     }
     return this.iamPolicyStub;
@@ -202,7 +202,7 @@ export class IamClient {
 
   getIamPolicy(
     request: protos.google.iam.v1.GetIamPolicyRequest,
-    options?: gax.CallOptions
+    options?: gax.CallOptions,
   ): Promise<[protos.google.iam.v1.Policy]>;
   getIamPolicy(
     request: protos.google.iam.v1.GetIamPolicyRequest,
@@ -211,7 +211,7 @@ export class IamClient {
       protos.google.iam.v1.Policy,
       protos.google.iam.v1.GetIamPolicyRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): void;
   getIamPolicy(
     request: protos.google.iam.v1.GetIamPolicyRequest,
@@ -219,7 +219,7 @@ export class IamClient {
       protos.google.iam.v1.Policy,
       protos.google.iam.v1.GetIamPolicyRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): void;
   getIamPolicy(
     request: protos.google.iam.v1.GetIamPolicyRequest,
@@ -234,7 +234,7 @@ export class IamClient {
       protos.google.iam.v1.Policy,
       protos.google.iam.v1.GetIamPolicyRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): Promise<[protos.google.iam.v1.Policy]> {
     let options: gax.CallOptions;
     if (optionsOrCallback instanceof Function && callback === undefined) {
@@ -255,13 +255,13 @@ export class IamClient {
       routingHeader.fromParams({
         resource: request.resource,
       });
-    this.initialize();
+    this.initialize().catch(console.error);
     return this.innerApiCalls.getIamPolicy(request, options, callback);
   }
 
   setIamPolicy(
     request: protos.google.iam.v1.SetIamPolicyRequest,
-    options?: gax.CallOptions
+    options?: gax.CallOptions,
   ): Promise<[protos.google.iam.v1.Policy]>;
   setIamPolicy(
     request: protos.google.iam.v1.SetIamPolicyRequest,
@@ -270,7 +270,7 @@ export class IamClient {
       protos.google.iam.v1.Policy,
       protos.google.iam.v1.SetIamPolicyRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): void;
   setIamPolicy(
     request: protos.google.iam.v1.SetIamPolicyRequest,
@@ -278,7 +278,7 @@ export class IamClient {
       protos.google.iam.v1.Policy,
       protos.google.iam.v1.SetIamPolicyRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): void;
   setIamPolicy(
     request: protos.google.iam.v1.SetIamPolicyRequest,
@@ -293,7 +293,7 @@ export class IamClient {
       protos.google.iam.v1.Policy,
       protos.google.iam.v1.SetIamPolicyRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): Promise<[protos.google.iam.v1.Policy]> {
     let options: gax.CallOptions;
     if (optionsOrCallback instanceof Function && callback === undefined) {
@@ -314,12 +314,12 @@ export class IamClient {
       routingHeader.fromParams({
         resource: request.resource,
       });
-    this.initialize();
+    this.initialize().catch(console.error);
     return this.innerApiCalls.setIamPolicy(request, options, callback);
   }
   testIamPermissions(
     request: protos.google.iam.v1.TestIamPermissionsRequest,
-    options?: gax.CallOptions
+    options?: gax.CallOptions,
   ): Promise<[protos.google.iam.v1.TestIamPermissionsResponse]>;
   testIamPermissions(
     request: protos.google.iam.v1.TestIamPermissionsRequest,
@@ -327,7 +327,7 @@ export class IamClient {
       protos.google.iam.v1.TestIamPermissionsResponse,
       protos.google.iam.v1.TestIamPermissionsRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): void;
   testIamPermissions(
     request: protos.google.iam.v1.TestIamPermissionsRequest,
@@ -336,7 +336,7 @@ export class IamClient {
       protos.google.iam.v1.TestIamPermissionsResponse,
       protos.google.iam.v1.TestIamPermissionsRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): void;
   testIamPermissions(
     request: protos.google.iam.v1.TestIamPermissionsRequest,
@@ -351,7 +351,7 @@ export class IamClient {
       protos.google.iam.v1.TestIamPermissionsResponse,
       protos.google.iam.v1.TestIamPermissionsRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): Promise<[protos.google.iam.v1.TestIamPermissionsResponse]> {
     let options: gax.CallOptions;
     if (optionsOrCallback instanceof Function && callback === undefined) {
@@ -372,7 +372,7 @@ export class IamClient {
       routingHeader.fromParams({
         resource: request.resource,
       });
-    this.initialize();
+    this.initialize().catch(console.error);
     return this.innerApiCalls.testIamPermissions(request, options, callback);
   }
 
@@ -382,7 +382,7 @@ export class IamClient {
    * The client will no longer be usable and all future behavior is undefined.
    */
   close(): Promise<void> {
-    this.initialize();
+    this.initialize().catch(console.error);
     if (!this._terminated) {
       return this.iamPolicyStub!.then(stub => {
         this._terminated = true;
@@ -407,7 +407,7 @@ export interface IamClient {
       protos.google.iam.v1.Policy,
       protos.google.iam.v1.GetIamPolicyRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): Promise<[protos.google.iam.v1.Policy]>;
   setIamPolicy(request: protos.google.iam.v1.SetIamPolicyRequest): void;
   setIamPolicy(
@@ -423,10 +423,10 @@ export interface IamClient {
       protos.google.iam.v1.Policy,
       protos.google.iam.v1.SetIamPolicyRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): Promise<[protos.google.iam.v1.Policy]>;
   testIamPermissions(
-    request: protos.google.iam.v1.TestIamPermissionsRequest
+    request: protos.google.iam.v1.TestIamPermissionsRequest,
   ): void;
   testIamPermissions(
     request: protos.google.iam.v1.TestIamPermissionsRequest,
@@ -441,6 +441,6 @@ export interface IamClient {
       protos.google.iam.v1.TestIamPermissionsResponse,
       protos.google.iam.v1.TestIamPermissionsRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): Promise<[protos.google.iam.v1.TestIamPermissionsResponse]>;
 }
diff --git a/gax/src/index.ts b/gax/src/index.ts
index 2393ce798..1baf2e566 100644
--- a/gax/src/index.ts
+++ b/gax/src/index.ts
@@ -76,7 +76,7 @@ export {OperationsClient} from './operationsClient';
 export {IamClient} from './iamService';
 export {LocationsClient} from './locationService';
 
-export const createByteLengthFunction = GrpcClient.createByteLengthFunction;
+export const createByteLengthFunction = GrpcClient?.createByteLengthFunction;
 export const version = require('../../package.json').version;
 
 import * as protobuf from 'protobufjs';
diff --git a/gax/src/locationService.ts b/gax/src/locationService.ts
index bfe49b865..08ed1b0cd 100644
--- a/gax/src/locationService.ts
+++ b/gax/src/locationService.ts
@@ -100,7 +100,7 @@ export class LocationsClient {
   constructor(
     gaxGrpc: GrpcClient | FallbackGrpcClient,
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    opts: ClientOptions
+    opts: ClientOptions,
   ) {
     // Ensure that options include all the required fields.
     this.gaxGrpc = gaxGrpc;
@@ -158,7 +158,7 @@ export class LocationsClient {
       listLocations: new PageDescriptor(
         'pageToken',
         'nextPageToken',
-        'locations'
+        'locations',
       ),
     };
 
@@ -167,7 +167,7 @@ export class LocationsClient {
       'google.cloud.location.Locations',
       gapicConfig as gax.ClientConfig,
       opts.clientConfig || {},
-      {'x-goog-api-client': clientHeader.join(' ')}
+      {'x-goog-api-client': clientHeader.join(' ')},
     );
 
     // Set up a dictionary of "inner API calls"; the core implementation
@@ -201,12 +201,12 @@ export class LocationsClient {
     this.locationsStub = this.gaxGrpc.createStub(
       this._opts.fallback
         ? (this._protos as protobuf.Root).lookupService(
-            'google.cloud.location.Locations'
+            'google.cloud.location.Locations',
           )
         : // eslint-disable-next-line @typescript-eslint/no-explicit-any
           (this._protos as any).google.cloud.location.Locations,
       this._opts,
-      this._providedCustomServicePath
+      this._providedCustomServicePath,
     ) as Promise<{[method: string]: Function}>;
 
     // Iterate over each of the methods that the service provides
@@ -224,14 +224,14 @@ export class LocationsClient {
           },
         (err: Error | null | undefined) => () => {
           throw err;
-        }
+        },
       );
 
       const descriptor = this.descriptors.page[methodName] || undefined;
       const apiCall = createApiCall(
         callPromise,
         this._defaults[methodName],
-        descriptor
+        descriptor,
       );
 
       this.innerApiCalls[methodName] = apiCall;
@@ -281,7 +281,7 @@ export class LocationsClient {
   getProjectId(): Promise<string>;
   getProjectId(callback: Callback<string, undefined, undefined>): void;
   getProjectId(
-    callback?: Callback<string, undefined, undefined>
+    callback?: Callback<string, undefined, undefined>,
   ): Promise<string> | void {
     if (callback) {
       this.auth.getProjectId(callback);
@@ -295,7 +295,7 @@ export class LocationsClient {
   // -------------------
   getLocation(
     request?: protos.google.cloud.location.IGetLocationRequest,
-    options?: gax.CallOptions
+    options?: gax.CallOptions,
   ): Promise<protos.google.cloud.location.ILocation>;
   getLocation(
     request: protos.google.cloud.location.IGetLocationRequest,
@@ -304,7 +304,7 @@ export class LocationsClient {
       protos.google.cloud.location.ILocation,
       protos.google.cloud.location.IGetLocationRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): void;
   getLocation(
     request: protos.google.cloud.location.IGetLocationRequest,
@@ -312,7 +312,7 @@ export class LocationsClient {
       protos.google.cloud.location.ILocation,
       protos.google.cloud.location.IGetLocationRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): void;
   /**
    * Gets information about a location.
@@ -344,7 +344,7 @@ export class LocationsClient {
       protos.google.cloud.location.ILocation,
       protos.google.cloud.location.IGetLocationRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): Promise<protos.google.cloud.location.ILocation> {
     request = request || {};
     let options: gax.CallOptions;
@@ -361,13 +361,13 @@ export class LocationsClient {
       routingHeader.fromParams({
         name: request.name || '',
       });
-    this.initialize();
+    this.initialize().catch(console.error);
     return this.innerApiCalls.getLocation(request, options, callback);
   }
 
   listLocations(
     request?: protos.google.cloud.location.IListLocationsRequest,
-    options?: gax.CallOptions
+    options?: gax.CallOptions,
   ): Promise<
     [
       protos.google.cloud.location.ILocation[],
@@ -382,7 +382,7 @@ export class LocationsClient {
       protos.google.cloud.location.IListLocationsRequest,
       protos.google.cloud.location.IListLocationsResponse | null | undefined,
       protos.google.cloud.location.ILocation
-    >
+    >,
   ): void;
   listLocations(
     request: protos.google.cloud.location.IListLocationsRequest,
@@ -390,7 +390,7 @@ export class LocationsClient {
       protos.google.cloud.location.IListLocationsRequest,
       protos.google.cloud.location.IListLocationsResponse | null | undefined,
       protos.google.cloud.location.ILocation
-    >
+    >,
   ): void;
   /**
    * Lists information about the supported locations for this service.
@@ -433,7 +433,7 @@ export class LocationsClient {
       protos.google.cloud.location.IListLocationsRequest,
       protos.google.cloud.location.IListLocationsResponse | null | undefined,
       protos.google.cloud.location.ILocation
-    >
+    >,
   ): Promise<
     [
       protos.google.cloud.location.ILocation[],
@@ -456,7 +456,7 @@ export class LocationsClient {
       routingHeader.fromParams({
         name: request.name || '',
       });
-    this.initialize();
+    this.initialize().catch(console.error);
     return this.innerApiCalls.listLocations(request, options, callback);
   }
 
@@ -492,7 +492,7 @@ export class LocationsClient {
    */
   listLocationsAsync(
     request: protos.google.cloud.location.IListLocationsRequest,
-    options?: gax.CallOptions
+    options?: gax.CallOptions,
   ): AsyncIterable<protos.google.cloud.location.ILocation> {
     request = request || {};
     options = options || {};
@@ -504,11 +504,11 @@ export class LocationsClient {
       });
     options = options || {};
     const callSettings = new gax.CallSettings(options);
-    this.initialize();
+    this.initialize().catch(console.error);
     return this.descriptors.page.listLocations.asyncIterate(
       this.innerApiCalls['listLocations'] as GaxCall,
       request as unknown as RequestType,
-      callSettings
+      callSettings,
     ) as AsyncIterable<protos.google.cloud.location.ILocation>;
   }
 
@@ -519,7 +519,7 @@ export class LocationsClient {
    * @returns {Promise} A promise that resolves when the client is closed.
    */
   close(): Promise<void> {
-    this.initialize();
+    this.initialize().catch(console.error);
     if (!this._terminated) {
       return this.locationsStub!.then(stub => {
         this._terminated = true;
@@ -545,11 +545,11 @@ export interface LocationsClient {
       protos.google.cloud.location.ILocation,
       protos.google.cloud.location.IGetLocationRequest | null | undefined,
       {} | null | undefined
-    >
+    >,
   ): Promise<protos.google.cloud.location.ILocation>;
 
   listLocationsAsync(
     request: protos.google.cloud.location.IListLocationsRequest,
-    options?: gax.CallOptions
+    options?: gax.CallOptions,
   ): AsyncIterable<protos.google.cloud.location.ILocation>;
 }
diff --git a/gax/src/longRunningCalls/longRunningApiCaller.ts b/gax/src/longRunningCalls/longRunningApiCaller.ts
index 7f4501dcc..c0c17f985 100644
--- a/gax/src/longRunningCalls/longRunningApiCaller.ts
+++ b/gax/src/longRunningCalls/longRunningApiCaller.ts
@@ -58,7 +58,7 @@ export class LongrunningApiCaller implements APICaller {
     apiCall: SimpleCallbackFunction,
     argument: {},
     settings: CallOptions,
-    canceller: OngoingCallPromise
+    canceller: OngoingCallPromise,
   ) {
     canceller.call((argument, callback) => {
       return this._wrapOperation(apiCall, settings, argument, callback);
@@ -69,7 +69,7 @@ export class LongrunningApiCaller implements APICaller {
     apiCall: SimpleCallbackFunction,
     settings: CallOptions,
     argument: {},
-    callback: APICallback
+    callback: APICallback,
   ) {
     let backoffSettings: BackoffSettings | undefined = settings.longrunning;
     if (!backoffSettings) {
@@ -89,11 +89,11 @@ export class LongrunningApiCaller implements APICaller {
           rawResponse as operationProtos.google.longrunning.Operation,
           longrunningDescriptor,
           backoffSettings!,
-          settings
+          settings,
         );
 
         callback(null, operation, rawResponse);
-      }
+      },
     );
   }
 
diff --git a/gax/src/longRunningCalls/longRunningDescriptor.ts b/gax/src/longRunningCalls/longRunningDescriptor.ts
index 673e167c5..58b823853 100644
--- a/gax/src/longRunningCalls/longRunningDescriptor.ts
+++ b/gax/src/longRunningCalls/longRunningDescriptor.ts
@@ -37,7 +37,7 @@ export class LongRunningDescriptor implements Descriptor {
   constructor(
     operationsClient: OperationsClient,
     responseDecoder: AnyDecoder,
-    metadataDecoder: AnyDecoder
+    metadataDecoder: AnyDecoder,
   ) {
     this.operationsClient = operationsClient;
     this.responseDecoder = responseDecoder;
diff --git a/gax/src/longRunningCalls/longrunning.ts b/gax/src/longRunningCalls/longrunning.ts
index e061ccf99..492406c08 100644
--- a/gax/src/longRunningCalls/longrunning.ts
+++ b/gax/src/longRunningCalls/longrunning.ts
@@ -37,7 +37,7 @@ export interface GetOperationCallback {
     err?: Error | null,
     result?: {},
     metadata?: {},
-    rawResponse?: LROOperation
+    rawResponse?: LROOperation,
   ): void;
 }
 
@@ -75,7 +75,7 @@ export class Operation extends EventEmitter {
     grpcOp: LROOperation,
     longrunningDescriptor: LongRunningDescriptor,
     backoffSettings: BackoffSettings,
-    callOptions?: CallOptions
+    callOptions?: CallOptions,
   ) {
     super();
     this.completeListeners = 0;
@@ -186,7 +186,7 @@ export class Operation extends EventEmitter {
     request.name = this.latestResponse.name;
     this.currentCallPromise_ = operationsClient.getOperationInternal(
       request,
-      this._callOptions!
+      this._callOptions!,
     );
 
     const noCallbackPromise = this.currentCallPromise_.then(
@@ -201,7 +201,7 @@ export class Operation extends EventEmitter {
           return;
         }
         return Promise.reject(err);
-      }
+      },
     );
 
     if (!callback) {
@@ -292,7 +292,7 @@ export class Operation extends EventEmitter {
 
       if (now.getTime() >= deadline) {
         const error = new GoogleError(
-          'Total timeout exceeded before any response was received'
+          'Total timeout exceeded before any response was received',
         );
         error.code = Status.DEADLINE_EXCEEDED;
         setImmediate(emit, 'error', error);
@@ -312,7 +312,7 @@ export class Operation extends EventEmitter {
               (rawResponse &&
                 !arrayEquals(
                   rawResponse.metadata.value!,
-                  previousMetadataBytes
+                  previousMetadataBytes,
                 )))
           ) {
             setImmediate(emit, 'progress', metadata, rawResponse);
@@ -353,7 +353,7 @@ export class Operation extends EventEmitter {
         'complete',
         (result, metadata, rawResponse) => {
           resolve([result, metadata, rawResponse]);
-        }
+        },
       );
     });
   }
@@ -376,7 +376,7 @@ export function operation(
   op: LROOperation,
   longrunningDescriptor: LongRunningDescriptor,
   backoffSettings: BackoffSettings,
-  callOptions?: CallOptions
+  callOptions?: CallOptions,
 ) {
   return new Operation(op, longrunningDescriptor, backoffSettings, callOptions);
 }
diff --git a/gax/src/normalCalls/normalApiCaller.ts b/gax/src/normalCalls/normalApiCaller.ts
index 50c424efb..b2da678f9 100644
--- a/gax/src/normalCalls/normalApiCaller.ts
+++ b/gax/src/normalCalls/normalApiCaller.ts
@@ -38,7 +38,7 @@ export class NormalApiCaller implements APICaller {
     apiCall: SimpleCallbackFunction,
     argument: {},
     settings: {},
-    canceller: OngoingCallPromise
+    canceller: OngoingCallPromise,
   ): void {
     canceller.call(apiCall, argument);
   }
diff --git a/gax/src/normalCalls/retries.ts b/gax/src/normalCalls/retries.ts
index ed67a4679..b0dc8c3c7 100644
--- a/gax/src/normalCalls/retries.ts
+++ b/gax/src/normalCalls/retries.ts
@@ -46,7 +46,7 @@ export function retryable(
   func: GRPCCall,
   retry: RetryOptions,
   otherArgs: GRPCCallOtherArgs,
-  apiName?: string
+  apiName?: string,
 ): SimpleCallbackFunction {
   const delayMult = retry.backoffSettings.retryDelayMultiplier;
   const maxDelay = retry.backoffSettings.maxRetryDelayMillis;
@@ -86,7 +86,7 @@ export function retryable(
             retry.backoffSettings.totalTimeoutMillis
           } milliseconds ${
             err ? `retrying error ${err} ` : ''
-          } before any response was received.`
+          } before any response was received.`,
         );
         error.code = Status.DEADLINE_EXCEEDED;
         callback(error);
@@ -97,7 +97,7 @@ export function retryable(
         const error = new GoogleError(
           'Exceeded maximum number of retries ' +
             (err ? `retrying error ${err} ` : '') +
-            'before any response was received'
+            'before any response was received',
         );
         error.code = Status.DEADLINE_EXCEEDED;
         callback(error);
@@ -149,7 +149,7 @@ export function retryable(
     if (maxRetries && deadline!) {
       const error = new GoogleError(
         'Cannot set both totalTimeoutMillis and maxRetries ' +
-          'in backoffSettings.'
+          'in backoffSettings.',
       );
       error.code = Status.INVALID_ARGUMENT;
       callback(error);
diff --git a/gax/src/normalCalls/timeout.ts b/gax/src/normalCalls/timeout.ts
index b1790d854..440a89cb5 100644
--- a/gax/src/normalCalls/timeout.ts
+++ b/gax/src/normalCalls/timeout.ts
@@ -40,7 +40,7 @@ export function addTimeoutArg(
   func: GRPCCall,
   timeout: number,
   otherArgs: GRPCCallOtherArgs,
-  abTests?: {}
+  abTests?: {},
 ): SimpleCallbackFunction {
   // TODO: this assumes the other arguments consist of metadata and options,
   // which is specific to gRPC calls. Remove the hidden dependency on gRPC.
diff --git a/gax/src/operationsClient.ts b/gax/src/operationsClient.ts
index 2941ff436..8cf71527c 100644
--- a/gax/src/operationsClient.ts
+++ b/gax/src/operationsClient.ts
@@ -70,7 +70,7 @@ export class OperationsClient {
     gaxGrpc: GrpcClient | FallbackGrpcClient,
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     operationsProtos: any,
-    options: ClientOptions
+    options: ClientOptions,
   ) {
     const opts = Object.assign(
       {
@@ -78,7 +78,7 @@ export class OperationsClient {
         port: DEFAULT_SERVICE_PORT,
         clientConfig: {},
       },
-      options
+      options,
     ) as ClientOptions & ClientStubOptions;
 
     const googleApiClient = ['gl-node/' + process.versions.node];
@@ -96,7 +96,7 @@ export class OperationsClient {
       'google.longrunning.Operations',
       configData,
       opts.clientConfig || {},
-      {'x-goog-api-client': googleApiClient.join(' ')}
+      {'x-goog-api-client': googleApiClient.join(' ')},
     );
 
     this.auth = gaxGrpc.auth;
@@ -109,7 +109,7 @@ export class OperationsClient {
       listOperations: new PageDescriptor(
         'pageToken',
         'nextPageToken',
-        'operations'
+        'operations',
       ),
     };
     // Put together the "service stub" for
@@ -118,7 +118,7 @@ export class OperationsClient {
       opts.fallback
         ? operationsProtos.lookupService('google.longrunning.Operations')
         : operationsProtos.google.longrunning.Operations,
-      opts
+      opts,
     ) as Promise<{[method: string]: Function}>;
     const operationsStubMethods = [
       'getOperation',
@@ -136,19 +136,19 @@ export class OperationsClient {
           },
         err => () => {
           throw err;
-        }
+        },
       );
       this.innerApiCalls[methodName] = createApiCall(
         innerCallPromise,
         defaults[methodName],
-        this.descriptor[methodName]
+        this.descriptor[methodName],
       );
     }
   }
 
   /** Closes this operations client. */
   close() {
-    this.operationsStub.then(stub => stub.close());
+    this.operationsStub.then(stub => stub.close()).catch(console.error);
   }
 
   /**
@@ -177,7 +177,7 @@ export class OperationsClient {
       protos.google.longrunning.Operation,
       protos.google.longrunning.GetOperationRequest,
       {} | null | undefined
-    >
+    >,
   ): CancellablePromise<ResultTuple> {
     request = request || {};
     options = options || {};
@@ -227,7 +227,7 @@ export class OperationsClient {
       protos.google.longrunning.Operation,
       protos.google.longrunning.GetOperationRequest,
       {} | null | undefined
-    >
+    >,
   ): Promise<[protos.google.longrunning.Operation]> {
     let options: gax.CallOptions;
     if (optionsOrCallback instanceof Function && callback === undefined) {
@@ -335,7 +335,7 @@ export class OperationsClient {
       protos.google.longrunning.ListOperationsResponse,
       protos.google.longrunning.ListOperationsRequest,
       {} | null | undefined
-    >
+    >,
   ): Promise<protos.google.longrunning.ListOperationsResponse> {
     let options: gax.CallOptions;
     if (optionsOrCallback instanceof Function && callback === undefined) {
@@ -399,13 +399,13 @@ export class OperationsClient {
    */
   listOperationsStream(
     request: protos.google.longrunning.ListOperationsRequest,
-    options?: gax.CallOptions
+    options?: gax.CallOptions,
   ): Transform {
     const callSettings = new gax.CallSettings(options);
     return this.descriptor.listOperations.createStream(
       this.innerApiCalls.listOperations as GaxCall,
       request,
-      callSettings
+      callSettings,
     );
   }
   /**
@@ -432,7 +432,7 @@ export class OperationsClient {
    */
   listOperationsAsync(
     request: protos.google.longrunning.ListOperationsRequest,
-    options?: gax.CallOptions
+    options?: gax.CallOptions,
   ): AsyncIterable<protos.google.longrunning.ListOperationsResponse> {
     request = request || {};
     options = options || {};
@@ -440,7 +440,7 @@ export class OperationsClient {
     return this.descriptor.listOperations.asyncIterate(
       this.innerApiCalls.listOperations as GaxCall,
       request as unknown as RequestType,
-      callSettings
+      callSettings,
     ) as AsyncIterable<protos.google.longrunning.ListOperationsResponse>;
   }
 
@@ -487,7 +487,7 @@ export class OperationsClient {
       protos.google.longrunning.CancelOperationRequest,
       protos.google.protobuf.Empty,
       {} | undefined | null
-    >
+    >,
   ): Promise<protos.google.protobuf.Empty> {
     let options: gax.CallOptions;
     if (optionsOrCallback instanceof Function && callback === undefined) {
@@ -542,7 +542,7 @@ export class OperationsClient {
       protos.google.protobuf.Empty,
       protos.google.longrunning.DeleteOperationRequest,
       {} | null | undefined
-    >
+    >,
   ): Promise<protos.google.protobuf.Empty> {
     let options: gax.CallOptions;
     if (optionsOrCallback instanceof Function && callback === undefined) {
@@ -570,7 +570,7 @@ export class OperationsClientBuilder {
    */
   constructor(
     gaxGrpc: GrpcClient | FallbackGrpcClient,
-    protoJson?: protobuf.Root
+    protoJson?: protobuf.Root,
   ) {
     if (protoJson && gaxGrpc.httpRules) {
       // overwrite the http rules if provide in service yaml.
diff --git a/gax/src/paginationCalls/pageDescriptor.ts b/gax/src/paginationCalls/pageDescriptor.ts
index 80aeb9766..13c3a4636 100644
--- a/gax/src/paginationCalls/pageDescriptor.ts
+++ b/gax/src/paginationCalls/pageDescriptor.ts
@@ -49,7 +49,7 @@ export class PageDescriptor implements Descriptor {
   constructor(
     requestPageTokenField: string,
     responsePageTokenField: string,
-    resourceField: string
+    resourceField: string,
   ) {
     this.requestPageTokenField = requestPageTokenField;
     this.responsePageTokenField = responsePageTokenField;
@@ -62,13 +62,13 @@ export class PageDescriptor implements Descriptor {
   createStream(
     apiCall: GaxCall,
     request: {},
-    options: CallSettings
+    options: CallSettings,
   ): Transform {
     if (options?.autoPaginate) {
       warn(
         'autoPaginate true',
         'Autopaginate will always be set to false in stream paging methods. See more info at https://github.com/googleapis/gax-nodejs/blob/main/client-libraries.md#auto-pagination for more information on how to configure paging calls',
-        'AutopaginateTrueWarning'
+        'AutopaginateTrueWarning',
       );
     }
     const stream = new PassThrough({objectMode: true});
@@ -80,7 +80,7 @@ export class PageDescriptor implements Descriptor {
       err: Error | null,
       resources: Array<ResponseType>,
       next: NextPageRequestType,
-      apiResp: RawResponseType
+      apiResp: RawResponseType,
     ) {
       if (err) {
         stream.emit('error', err);
@@ -128,10 +128,10 @@ export class PageDescriptor implements Descriptor {
         setImmediate(apiCall, next, options, callback as APICallback);
       }
     }
-    stream.on('resume', () => {
+    stream.on('resume', async () => {
       if (!started) {
         started = true;
-        apiCall(request, options, callback as unknown as APICallback);
+        await apiCall(request, options, callback as unknown as APICallback);
       }
     });
     return stream;
@@ -143,13 +143,13 @@ export class PageDescriptor implements Descriptor {
   asyncIterate(
     apiCall: GaxCall,
     request: RequestType,
-    options?: CallSettings
+    options?: CallSettings,
   ): AsyncIterable<{} | undefined> {
     if (options?.autoPaginate) {
       warn(
         'autoPaginate true',
         'Autopaginate will always be set to false in Async paging methods. See more info at https://github.com/googleapis/gax-nodejs/blob/main/client-libraries.md#auto-pagination for more information on how to configure paging calls',
-        'AutopaginateTrueWarning'
+        'AutopaginateTrueWarning',
       );
     }
     options = Object.assign({}, options, {autoPaginate: false});
@@ -160,7 +160,7 @@ export class PageDescriptor implements Descriptor {
   createIterator(
     apiCall: GaxCall,
     request: RequestType,
-    options: CallSettings
+    options: CallSettings,
   ): AsyncIterable<{} | undefined> {
     const asyncIterable = {
       [Symbol.asyncIterator]() {
@@ -179,7 +179,7 @@ export class PageDescriptor implements Descriptor {
               let result: {} | [ResponseType] | null;
               [result, nextPageRequest] = (await apiCall(
                 nextPageRequest!,
-                options
+                options,
               )) as ResultTuple;
               // For pagination response with protobuf map type, use tuple as representation.
               if (result && !Array.isArray(result)) {
diff --git a/gax/src/paginationCalls/pagedApiCaller.ts b/gax/src/paginationCalls/pagedApiCaller.ts
index bf92b76cc..e22bcf3f5 100644
--- a/gax/src/paginationCalls/pagedApiCaller.ts
+++ b/gax/src/paginationCalls/pagedApiCaller.ts
@@ -59,7 +59,7 @@ export class PagedApiCaller implements APICaller {
    */
   private generateParseResponseCallback(
     request: NextPageRequestType,
-    callback: APICallback
+    callback: APICallback,
   ): APICallback {
     const resourceFieldName = this.pageDescriptor.resourceField;
     const responsePageTokenFieldName =
@@ -72,13 +72,13 @@ export class PagedApiCaller implements APICaller {
       }
       if (!request) {
         callback(
-          new GoogleError('Undefined request in pagination method callback.')
+          new GoogleError('Undefined request in pagination method callback.'),
         );
         return;
       }
       if (!response) {
         callback(
-          new GoogleError('Undefined response in pagination method callback.')
+          new GoogleError('Undefined response in pagination method callback.'),
         );
         return;
       }
@@ -109,7 +109,7 @@ export class PagedApiCaller implements APICaller {
         argument,
         metadata,
         options,
-        self.generateParseResponseCallback(argument, callback)
+        self.generateParseResponseCallback(argument, callback),
       );
     };
   }
@@ -144,7 +144,7 @@ export class PagedApiCaller implements APICaller {
     apiCall: SimpleCallbackFunction,
     request: RequestType,
     settings: CallOptions,
-    ongoingCall: OngoingCall
+    ongoingCall: OngoingCall,
   ) {
     request = Object.assign({}, request);
 
@@ -157,7 +157,7 @@ export class PagedApiCaller implements APICaller {
       warn(
         'autoPaginate true',
         'Providing a pageSize without setting autoPaginate to false will still return all results. See https://github.com/googleapis/gax-nodejs/blob/main/client-libraries.md#auto-pagination for more information on how to configure manual paging',
-        'AutopaginateTrueWarning'
+        'AutopaginateTrueWarning',
       );
     }
 
@@ -166,7 +166,7 @@ export class PagedApiCaller implements APICaller {
     const resourceCollector = new ResourceCollector(apiCall, maxResults);
     resourceCollector.processAllPages(request).then(
       resources => ongoingCall.callback(null, resources),
-      err => ongoingCall.callback(err)
+      err => ongoingCall.callback(err),
     );
   }
 
diff --git a/gax/src/paginationCalls/resourceCollector.ts b/gax/src/paginationCalls/resourceCollector.ts
index 268b5b143..bf64a374b 100644
--- a/gax/src/paginationCalls/resourceCollector.ts
+++ b/gax/src/paginationCalls/resourceCollector.ts
@@ -45,7 +45,7 @@ export class ResourceCollector {
   private callback(
     err: Error | null,
     resources: Array<{}>,
-    nextPageRequest: NextPageRequestType
+    nextPageRequest: NextPageRequestType,
   ) {
     if (err) {
       // Something went wrong with this request - failing everything
diff --git a/gax/src/pathTemplate.ts b/gax/src/pathTemplate.ts
index ae208448c..636b90db7 100644
--- a/gax/src/pathTemplate.ts
+++ b/gax/src/pathTemplate.ts
@@ -52,11 +52,11 @@ export class PathTemplate {
       // if the path contains a wildcard, then the length may differ by 1.
       if (!this.data.includes('**')) {
         throw new TypeError(
-          `This path ${path} does not match path template ${this.data}, the number of parameters is not same.`
+          `This path ${path} does not match path template ${this.data}, the number of parameters is not same.`,
         );
       } else if (pathSegments.length !== this.segments.length + 1) {
         throw new TypeError(
-          `This path ${path} does not match path template ${this.data}, the number of parameters is not same with one wildcard.`
+          `This path ${path} does not match path template ${this.data}, the number of parameters is not same with one wildcard.`,
         );
       }
     }
@@ -68,18 +68,18 @@ export class PathTemplate {
       if (this.segments[index] !== pathSegments[0]) {
         if (!this.segments[index].includes('*')) {
           throw new TypeError(
-            `segment does not match, ${this.segments[index]} and  ${pathSegments[index]}.`
+            `segment does not match, ${this.segments[index]} and  ${pathSegments[index]}.`,
           );
         } else {
           let segment = this.segments[index];
           const matches = segment.match(/\{[$0-9a-zA-Z_]+=.*?\}/g);
           if (!matches) {
             throw new Error(
-              `Error processing path template segment ${segment}`
+              `Error processing path template segment ${segment}`,
             );
           }
           const variables = matches.map(str =>
-            str.replace(/^\{/, '').replace(/=.*/, '')
+            str.replace(/^\{/, '').replace(/=.*/, ''),
           );
           if (segment.includes('**')) {
             bindings[variables[0]] = pathSegments[0] + '/' + pathSegments[1];
@@ -96,7 +96,7 @@ export class PathTemplate {
               const value = pathSegments[0].split(/[-_.~]/);
               if (value.length !== variables.length) {
                 throw new Error(
-                  `segment ${segment} does not match ${pathSegments[0]}`
+                  `segment ${segment} does not match ${pathSegments[0]}`,
                 );
               }
               for (const v of variables) {
@@ -107,7 +107,7 @@ export class PathTemplate {
               // segment: {blurb_id=*}.{legacy_user=*} matching pathSegments: ['bar~user2'] should fail
               if (segment !== pathSegments[0]) {
                 throw new TypeError(
-                  `non slash resource pattern ${this.segments[index]} and ${pathSegments[0]} should have same separator`
+                  `non slash resource pattern ${this.segments[index]} and ${pathSegments[0]} should have same separator`,
                 );
               }
             }
@@ -136,7 +136,7 @@ export class PathTemplate {
           Object.keys(bindings).length
         } does not match the number of needed variables ${
           Object.keys(this.bindings).length
-        }`
+        }`,
       );
     }
     let path = this.inspect();
@@ -195,11 +195,11 @@ export class PathTemplate {
       } else if ((matches = segment.match(/\{[0-9a-zA-Z-.~_]+(?:=.*?)?\}/g))) {
         for (const subsegment of matches) {
           const pairMatch = subsegment.match(
-            /^\{([0-9a-zA-Z-.~_]+)(?:=(.*?))?\}$/
+            /^\{([0-9a-zA-Z-.~_]+)(?:=(.*?))?\}$/,
           );
           if (!pairMatch) {
             throw new Error(
-              `Cannot process path template segment ${subsegment}`
+              `Cannot process path template segment ${subsegment}`,
             );
           }
           const key = pairMatch[1];
diff --git a/gax/src/streamArrayParser.ts b/gax/src/streamArrayParser.ts
index 7aa03c1f4..4d001894a 100644
--- a/gax/src/streamArrayParser.ts
+++ b/gax/src/streamArrayParser.ts
@@ -75,9 +75,9 @@ export class StreamArrayParser extends Transform {
           'error',
           new Error(
             `Internal Error: API service stream data must start with a '[' and close with the corresponding ']', but it start with ${String.fromCharCode(
-              chunk[0]
-            )}`
-          )
+              chunk[0],
+            )}`,
+          ),
         );
       }
       curIndex++;
diff --git a/gax/src/streamingCalls/streamDescriptor.ts b/gax/src/streamingCalls/streamDescriptor.ts
index fc6090d09..2ac1490fb 100644
--- a/gax/src/streamingCalls/streamDescriptor.ts
+++ b/gax/src/streamingCalls/streamDescriptor.ts
@@ -31,7 +31,7 @@ export class StreamDescriptor implements Descriptor {
   constructor(
     streamType: StreamType,
     rest?: boolean,
-    gaxStreamingRetries?: boolean
+    gaxStreamingRetries?: boolean,
   ) {
     this.type = streamType;
     this.streaming = true;
diff --git a/gax/src/streamingCalls/streaming.ts b/gax/src/streamingCalls/streaming.ts
index 7e22e2399..81f656604 100644
--- a/gax/src/streamingCalls/streaming.ts
+++ b/gax/src/streamingCalls/streaming.ts
@@ -55,17 +55,17 @@ export interface DuplexifyConstructor {
   obj(
     writable?: Writable | false | null,
     readable?: Readable | false | null,
-    options?: DuplexifyOptions
+    options?: DuplexifyOptions,
   ): Duplexify;
   new (
     writable?: Writable | false | null,
     readable?: Readable | false | null,
-    options?: DuplexifyOptions
+    options?: DuplexifyOptions,
   ): Duplexify;
   (
     writable?: Writable | false | null,
     readable?: Readable | false | null,
-    options?: DuplexifyOptions
+    options?: DuplexifyOptions,
   ): Duplexify;
 }
 
@@ -117,7 +117,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
     type: StreamType,
     callback: APICallback,
     rest?: boolean,
-    gaxServerStreamingRetries?: boolean
+    gaxServerStreamingRetries?: boolean,
   ) {
     super(undefined, undefined, {
       objectMode: true,
@@ -163,7 +163,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
     totalTimeoutMillis: number,
     originalError: GoogleError,
     originalTimeout: number | undefined,
-    retries: number
+    retries: number,
   ): void {
     const now = new Date();
 
@@ -177,7 +177,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
       const error = new GoogleError(
         `Total timeout of API exceeded ${originalTimeout} milliseconds ${
           originalError ? `retrying error ${originalError} ` : ''
-        } before any response was received.`
+        } before any response was received.`,
       );
       error.code = Status.DEADLINE_EXCEEDED;
       throw error;
@@ -191,7 +191,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
       const error = new GoogleError(
         'Exceeded maximum number of retries ' +
           (originalError ? `retrying error ${originalError} ` : '') +
-          'before any response was received'
+          'before any response was received',
       );
       error.code = Status.DEADLINE_EXCEEDED;
       throw error;
@@ -298,7 +298,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
     apiCall: SimpleCallbackFunction,
     argument: {},
     retryRequestOptions: RetryRequestOptions = {},
-    retry: RetryOptions
+    retry: RetryOptions,
   ) {
     this.apiCall = apiCall;
     this.argument = argument;
@@ -335,7 +335,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
             }
             const stream = apiCall(
               argument,
-              this._callback
+              this._callback,
             ) as CancellableStream;
             this.stream = stream;
             this.forwardEvents(stream);
@@ -378,7 +378,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
    * @returns {CancellableStream} - the stream that handles retry logic
    */
   private newStreamingRetryRequest(
-    opts: streamingRetryRequestOptions
+    opts: streamingRetryRequestOptions,
   ): CancellableStream {
     // at this point, it would be unexpected if retry were undefined
     // but if it is, provide a logical default so we don't run into trouble
@@ -402,7 +402,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
     }
     const transientErrorHelper = (
       error: Error,
-      requestStream: CancellableStream
+      requestStream: CancellableStream,
     ) => {
       const e = GoogleError.parseGRPCStatusDetails(error);
       e.note =
@@ -493,7 +493,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
             if (maxRetries && totalTimeout) {
               const newError = new GoogleError(
                 'Cannot set both totalTimeoutMillis and maxRetries ' +
-                  'in backoffSettings.'
+                  'in backoffSettings.',
               );
               newError.code = Status.INVALID_ARGUMENT;
               // clean up the request stream and retryStreams, silently destroy it on the request stream
@@ -512,11 +512,11 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
                   timeout!,
                   error,
                   totalTimeout,
-                  retries
+                  retries,
                 );
               } catch (error: unknown) {
                 const e = GoogleError.parseGRPCStatusDetails(
-                  error as GoogleError
+                  error as GoogleError,
                 );
                 // clean up the request stream and retryStreams, silently destroy it on the request stream
                 // but do raise it on destruction of the retryStream so the consumer can see it
@@ -563,7 +563,7 @@ export class StreamProxy extends duplexify implements GRPCCallResult {
                     }
                     const newStream = this.apiCall!(
                       retryArgument,
-                      this._callback
+                      this._callback,
                     ) as CancellableStream;
                     return newStream;
                   };
diff --git a/gax/src/streamingCalls/streamingApiCaller.ts b/gax/src/streamingCalls/streamingApiCaller.ts
index 68ddb9855..66bc77fe7 100644
--- a/gax/src/streamingCalls/streamingApiCaller.ts
+++ b/gax/src/streamingCalls/streamingApiCaller.ts
@@ -48,7 +48,7 @@ export class StreamingApiCaller implements APICaller {
       this.descriptor.type,
       callback,
       this.descriptor.rest,
-      this.descriptor.gaxStreamingRetries
+      this.descriptor.gaxStreamingRetries,
     );
   }
 
@@ -63,7 +63,7 @@ export class StreamingApiCaller implements APICaller {
           argument: {},
           metadata: {},
           options: {},
-          callback?: APICallback
+          callback?: APICallback,
         ) => {
           return (func as ClientStreamingCall)(metadata, options, callback);
         };
@@ -74,7 +74,7 @@ export class StreamingApiCaller implements APICaller {
       default:
         warn(
           'streaming_wrap_unknown_stream_type',
-          `Unknown stream type: ${this.descriptor.type}`
+          `Unknown stream type: ${this.descriptor.type}`,
         );
     }
     return func;
@@ -84,13 +84,13 @@ export class StreamingApiCaller implements APICaller {
     apiCall: SimpleCallbackFunction,
     argument: {},
     settings: CallSettings,
-    stream: StreamProxy
+    stream: StreamProxy,
   ) {
     stream.setStream(
       apiCall,
       argument,
       settings.retryRequestOptions,
-      settings.retry!
+      settings.retry!,
     );
   }
 
diff --git a/gax/src/transcoding.ts b/gax/src/transcoding.ts
index d4cdf614b..37b399f50 100644
--- a/gax/src/transcoding.ts
+++ b/gax/src/transcoding.ts
@@ -50,7 +50,7 @@ export type ParsedOptionsType = Array<
 export function getField(
   request: JSONObject,
   field: string,
-  allowObjects = false // in most cases, we need leaf fields
+  allowObjects = false, // in most cases, we need leaf fields
 ): JSONValue | undefined {
   const parts = field.split('.');
   let value: JSONValue = request;
@@ -74,7 +74,7 @@ export function getField(
 export function deepCopyWithoutMatchedFields(
   request: JSONObject,
   fieldsToSkip: Set<string>,
-  fullNamePrefix = ''
+  fullNamePrefix = '',
 ): JSONObject {
   if (typeof request !== 'object' || request === null) {
     return request;
@@ -89,13 +89,13 @@ export function deepCopyWithoutMatchedFields(
     if (Array.isArray(copy[key])) {
       // a field of an array cannot be addressed as "request.field", so we omit the skipping logic for array descendants
       copy[key] = (copy[key] as JSONObject[]).map(value =>
-        deepCopyWithoutMatchedFields(value, new Set())
+        deepCopyWithoutMatchedFields(value, new Set()),
       );
     } else if (typeof copy[key] === 'object' && copy[key] !== null) {
       copy[key] = deepCopyWithoutMatchedFields(
         copy[key] as JSONObject,
         fieldsToSkip,
-        nextFullNamePrefix
+        nextFullNamePrefix,
       );
     }
   }
@@ -120,7 +120,7 @@ export function deleteField(request: JSONObject, field: string): void {
 
 export function buildQueryStringComponents(
   request: JSONObject,
-  prefix = ''
+  prefix = '',
 ): string[] {
   const resultList = [];
   for (const key in request) {
@@ -128,19 +128,19 @@ export function buildQueryStringComponents(
       for (const value of request[key] as JSONObject[]) {
         resultList.push(
           `${prefix}${encodeWithoutSlashes(key)}=${encodeWithoutSlashes(
-            value.toString()
-          )}`
+            value.toString(),
+          )}`,
         );
       }
     } else if (typeof request[key] === 'object' && request[key] !== null) {
       resultList.push(
-        ...buildQueryStringComponents(request[key] as JSONObject, `${key}.`)
+        ...buildQueryStringComponents(request[key] as JSONObject, `${key}.`),
       );
     } else {
       resultList.push(
         `${prefix}${encodeWithoutSlashes(key)}=${encodeWithoutSlashes(
-          request[key] === null ? 'null' : request[key]!.toString()
-        )}`
+          request[key] === null ? 'null' : request[key]!.toString(),
+        )}`,
       );
     }
   }
@@ -167,7 +167,7 @@ function escapeRegExp(str: string) {
 
 export function applyPattern(
   pattern: string,
-  fieldValue: string
+  fieldValue: string,
 ): string | undefined {
   if (!pattern || pattern === '*') {
     return encodeWithSlashes(fieldValue);
@@ -183,7 +183,7 @@ export function applyPattern(
       escapeRegExp(pattern)
         .replace(/\\\*\\\*/g, '(.+)')
         .replace(/\\\*/g, '([^/]+)') +
-      '$'
+      '$',
   );
 
   if (!fieldValue.match(regex)) {
@@ -205,7 +205,7 @@ interface MatchResult {
 
 export function match(
   request: JSONObject,
-  pattern: string
+  pattern: string,
 ): MatchResult | undefined {
   let url = pattern;
   const matchedFields = [];
@@ -223,7 +223,7 @@ export function match(
     }
     const appliedPattern = applyPattern(
       pattern,
-      fieldValue === null ? 'null' : fieldValue!.toString()
+      fieldValue === null ? 'null' : fieldValue!.toString(),
     );
     if (appliedPattern === undefined) {
       return undefined;
@@ -268,7 +268,7 @@ export function isProto3OptionalField(field: Field) {
 
 export function transcode(
   request: JSONObject,
-  parsedOptions: ParsedOptionsType
+  parsedOptions: ParsedOptionsType,
 ): TranscodedRequest | undefined {
   const httpRules = [];
   for (const option of parsedOptions) {
@@ -313,7 +313,7 @@ export function transcode(
         data = getField(
           queryStringObject,
           fieldToCamelCase(httpRule.body),
-          /*allowObjects:*/ true
+          /*allowObjects:*/ true,
         );
         deleteField(queryStringObject, fieldToCamelCase(httpRule.body));
       } else {
@@ -337,7 +337,7 @@ export function transcode(
 // Override the protobuf json's the http rules.
 export function overrideHttpRules(
   httpRules: Array<google.api.IHttpRule>,
-  protoJson: protobuf.Root
+  protoJson: protobuf.Root,
 ) {
   for (const rule of httpRules) {
     if (!rule.selector) {
diff --git a/gax/src/util.ts b/gax/src/util.ts
index 8aab5e316..e52e241ef 100644
--- a/gax/src/util.ts
+++ b/gax/src/util.ts
@@ -13,7 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import {v4 as uuidv4} from 'uuid';
+const randomUUID = () =>
+  globalThis.crypto?.randomUUID() || require('crypto').randomUUID();
 
 function words(str: string, normalize = false) {
   if (normalize) {
@@ -88,7 +89,7 @@ export function toCamelCase(str: string) {
         return '_' + w;
       }
       return capitalize(w);
-    })
+    }),
   );
   return result.join('');
 }
@@ -110,5 +111,5 @@ export function toLowerCamelCase(str: string) {
  * in lower case).
  */
 export function makeUUID() {
-  return uuidv4();
+  return randomUUID();
 }
diff --git a/gax/test/browser-test/karma.conf.js b/gax/test/browser-test/karma.conf.js
index 8b79b3868..db543d346 100644
--- a/gax/test/browser-test/karma.conf.js
+++ b/gax/test/browser-test/karma.conf.js
@@ -30,26 +30,23 @@ module.exports = function (config) {
   config.set({
     // base path that will be used to resolve all patterns (eg. files, exclude)
     basePath: '',
-
     // frameworks to use
     // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
     frameworks: ['mocha', 'child-process'],
+    files: ['./test/*.ts'],
 
     client: {
       childProcess: {
         path: path.relative(
           process.cwd(),
           // eslint-disable-next-line n/no-missing-require
-          require.resolve('showcase-server/build/src/index.js')
+          require.resolve('showcase-server/build/src/index.js'),
         ),
         args: [],
         options: {},
       },
     },
 
-    // list of files / patterns to load in the browser
-    files: ['./test/test.*.ts'],
-
     // list of files / patterns to exclude
     exclude: [],
 
@@ -60,7 +57,6 @@ module.exports = function (config) {
     },
 
     webpack: webpackConfig,
-
     // test results reporter to use
     // possible values: 'dots', 'progress'
     // available reporters: https://npmjs.org/browse/keyword/karma-reporter
@@ -96,14 +92,16 @@ module.exports = function (config) {
     // Continuous Integration mode
     // if true, Karma captures browsers, runs the tests and exits
     singleRun: true,
-
+    // list of files / patterns to load in the browser
     // Concurrency level
     // how many browser should be started simultaneous
     concurrency: Infinity,
-
     // set correct MIME type when serving .ts files (already compiled to JavaScript):
     mime: {
       'text/javascript': ['ts'],
     },
+    browserDisconnectTimeout: 60000, // Increase to 60 seconds (or more)
+    browserNoActivityTimeout: 60000,
+    mode: 'development',
   });
 };
diff --git a/gax/test/browser-test/package.json b/gax/test/browser-test/package.json
index 5171769db..e98611d88 100644
--- a/gax/test/browser-test/package.json
+++ b/gax/test/browser-test/package.json
@@ -8,7 +8,7 @@
     "build/test"
   ],
   "engines": {
-    "node": ">=14"
+    "node": ">=18"
   },
   "license": "Apache-2.0",
   "keywords": [],
@@ -25,23 +25,31 @@
   },
   "devDependencies": {
     "@types/mocha": "^9.1.1",
-    "@types/node": "^14.11.2",
+    "@types/node": "^20.5.0",
     "@types/sinon": "^10.0.13",
+    "assert": "^2.1.0",
+    "core-js": "^3.40.0",
     "google-gax": "./google-gax.tgz",
+    "https-browserify": "^1.0.0",
     "is-docker": "^2.2.1",
-    "karma": "^6.0.0",
-    "karma-child-process": "^1.0.3",
-    "karma-chrome-launcher": "^3.0.0",
-    "karma-mocha": "^2.0.0",
-    "karma-sourcemap-loader": "^0.3.7",
-    "karma-webpack": "^4.0.0",
+    "karma": "^6.4.4",
+    "karma-child-process": "^1.0.14",
+    "karma-chrome-launcher": "^3.2.0",
+    "karma-mocha": "^2.0.1",
+    "karma-sourcemap-loader": "^0.4.0",
+    "karma-webpack": "^5.0.1",
     "mocha": "^10.0.0",
+    "process": "^0.11.10",
     "puppeteer": "^16.0.0",
+    "querystring-es3": "^0.2.1",
     "showcase-echo-client": "./showcase-echo-client.tgz",
     "showcase-server": "./showcase-server.tgz",
     "sinon": "^14.0.0",
-    "typescript": "^4.0.3",
-    "webpack": "^4.0.0",
+    "stream-browserify": "^3.0.0",
+    "stream-http": "^3.2.0",
+    "typescript": "^5.7.3",
+    "url": "^0.11.4",
+    "webpack": "^5.97.1",
     "webpack-cli": "^4.0.0"
   }
 }
diff --git a/gax/test/browser-test/test/test.endtoend.ts b/gax/test/browser-test/test/test.endtoend.ts
index 1d9556dbc..77cec9f94 100644
--- a/gax/test/browser-test/test/test.endtoend.ts
+++ b/gax/test/browser-test/test/test.endtoend.ts
@@ -18,6 +18,7 @@ import * as assert from 'assert';
 import {describe, it, before} from 'mocha';
 import {GoogleAuth} from 'google-gax';
 import {EchoClient} from 'showcase-echo-client';
+import 'core-js/stable';
 
 function sleep(timeout: number) {
   return new Promise(resolve => {
@@ -25,7 +26,7 @@ function sleep(timeout: number) {
   });
 }
 
-describe('Run tests against gRPC server', () => {
+describe('Run tests against gRPC server', async function () {
   const authStub = {
     getClient: async () => {
       return {
@@ -76,6 +77,7 @@ describe('Run tests against gRPC server', () => {
   });
 
   it('should be able to call simple RPC methods', async () => {
+    this.timeout(80000);
     const request = {
       content: 'test',
     };
diff --git a/gax/test/browser-test/test/test.grpc-fallback.ts b/gax/test/browser-test/test/test.grpc-fallback.ts
index 768242e9b..1b294036d 100644
--- a/gax/test/browser-test/test/test.grpc-fallback.ts
+++ b/gax/test/browser-test/test/test.grpc-fallback.ts
@@ -21,6 +21,7 @@ import {after, afterEach, before, beforeEach, describe, it} from 'mocha';
 import * as sinon from 'sinon';
 import {protobuf, GoogleAuth, fallback} from 'google-gax';
 import {EchoClient} from 'showcase-echo-client';
+import 'core-js/stable';
 
 import echoProtoJson = require('showcase-echo-client/build/protos/protos.json');
 
diff --git a/gax/test/browser-test/tsconfig.json b/gax/test/browser-test/tsconfig.json
index 696defbe7..21b519c62 100644
--- a/gax/test/browser-test/tsconfig.json
+++ b/gax/test/browser-test/tsconfig.json
@@ -4,10 +4,11 @@
     "rootDir": ".",
     "outDir": "build",
     "resolveJsonModule": true,
-    "lib": ["ES2018", "DOM"]
+    "lib": ["DOM"]
   },
   "include": [
     "src/**/*.ts",
-    "test/**/*.ts"
+    "test/**/*.ts",
+    "src/**/*.json",
   ]
 }
diff --git a/gax/test/browser-test/webpack.config.js b/gax/test/browser-test/webpack.config.js
index b8a8b6a11..448e04819 100644
--- a/gax/test/browser-test/webpack.config.js
+++ b/gax/test/browser-test/webpack.config.js
@@ -13,12 +13,34 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+/* eslint-disable n/no-missing-require */
 
+const webpack = require('webpack');
 module.exports = {
   entry: './build/src/index.js',
   resolve: {
     extensions: ['.ts', '.js', '.json'],
+    fallback: {
+      fs: 'empty',
+      child_process: 'empty',
+      // eslint-disable-next-line n/no-extraneous-require
+      assert: require.resolve('assert/'),
+      util: require.resolve('util'),
+      stream: require.resolve('stream-browserify'),
+      http: require.resolve('stream-http'),
+      https: require.resolve('https-browserify'),
+      querystring: require.resolve('querystring-es3'),
+      url: require.resolve('url/'),
+    },
   },
+  plugins: [
+    new webpack.ProvidePlugin({
+      process: 'process/browser',
+    }),
+    new webpack.ProvidePlugin({
+      Buffer: ['buffer', 'Buffer'],
+    }),
+  ],
   module: {
     rules: [
       {
@@ -44,9 +66,6 @@ module.exports = {
       },
     ],
   },
-  node: {
-    fs: 'empty',
-    child_process: 'empty',
-  },
-  mode: 'production',
+  cache: false,
+  mode: 'development',
 };
diff --git a/gax/test/showcase-echo-client/package.json b/gax/test/showcase-echo-client/package.json
index 3720c326f..e4dc00ed7 100644
--- a/gax/test/showcase-echo-client/package.json
+++ b/gax/test/showcase-echo-client/package.json
@@ -37,9 +37,9 @@
   "devDependencies": {
     "@types/node": "^20.11.26",
     "gapic-tools": "./gapic-tools.tgz",
-    "typescript": "^4.5.5"
+    "typescript": "^5.7.3"
   },
   "engines": {
-    "node": ">=v14"
+    "node": ">=v18"
   }
 }
diff --git a/gax/test/showcase-echo-client/tsconfig.json b/gax/test/showcase-echo-client/tsconfig.json
index 81cb00448..e43e06476 100644
--- a/gax/test/showcase-echo-client/tsconfig.json
+++ b/gax/test/showcase-echo-client/tsconfig.json
@@ -12,5 +12,7 @@
   "include": [
     "src/*.ts",
     "src/**/*.ts",
+    "src/**/*.json",
+    "protos/protos.json"
   ]
 }
diff --git a/gax/test/showcase-server/package.json b/gax/test/showcase-server/package.json
index 327552427..54d7cd6bd 100644
--- a/gax/test/showcase-server/package.json
+++ b/gax/test/showcase-server/package.json
@@ -22,10 +22,10 @@
   },
   "devDependencies": {
     "@types/download": "^8.0.1",
-    "@types/node": "^14.11.2",
-    "typescript": "^4.0.3"
+    "@types/node": "^18.11.2",
+    "typescript": "^5.7.3"
   },
   "engines": {
-     "node": ">=14"
+     "node": ">=18"
   }
 }
diff --git a/gax/test/system-test/test.clientlibs.ts b/gax/test/system-test/test.clientlibs.ts
index b236a7b3e..56867dbce 100644
--- a/gax/test/system-test/test.clientlibs.ts
+++ b/gax/test/system-test/test.clientlibs.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as execa from 'execa';
+import execa from 'execa';
 import * as fs from 'fs';
 import * as fsp from 'fs/promises';
 import * as path from 'path';
@@ -43,7 +43,7 @@ const toolsTarball = path.join(gaxDir, toolsBasename);
 
 async function latestRelease(
   cwd: string,
-  inMonorepo: boolean
+  inMonorepo: boolean,
 ): Promise<string> {
   // tags in the monorepo follow the format <libraryname>-major.minor.patch e.g. batch-0.0.1
   // or the format <libraryname>-vmajor.minor.patch e.g. batch-v0.0.1
@@ -84,12 +84,12 @@ async function latestRelease(
 function monoRepoPackageSubdirectory(packageName: string): string {
   return `${monoRepoDirectory}/packages/google-cloud-${packageName.replace(
     '-',
-    ''
+    '',
   )}`;
 }
 async function preparePackage(
   packageName: string,
-  inMonorepo: boolean
+  inMonorepo: boolean,
 ): Promise<void> {
   // clone googleapis/google-cloud node if monorepo, googleapis/nodejs-<package> if not
   const repoUrl = inMonorepo
@@ -101,7 +101,7 @@ async function preparePackage(
       await execa(
         'git',
         ['clone', repoUrl, inMonorepo ? monoRepoDirectory : packageName],
-        {stdio: 'inherit'}
+        {stdio: 'inherit'},
       );
       clonedRepos.push(repoUrl);
     } catch (error: unknown) {
@@ -118,7 +118,7 @@ async function preparePackage(
   const packagePath = monoRepoPackageSubdirectory(packageName); // used if in monoRepo
   const packageJson = path.join(
     inMonorepo ? packagePath : packageName,
-    'package.json'
+    'package.json',
   );
   const packageJsonStr = (await readFile(packageJson)).toString();
   const packageJsonObj = JSON.parse(packageJsonStr);
@@ -140,7 +140,7 @@ enum TestResult {
 async function runScript(
   packageName: string,
   inMonorepo: boolean,
-  script: string
+  script: string,
 ): Promise<TestResult> {
   try {
     await execa('npm', ['run', script], {
@@ -160,7 +160,7 @@ async function runScript(
 
 async function runSystemTest(
   packageName: string,
-  inMonorepo: boolean
+  inMonorepo: boolean,
 ): Promise<TestResult> {
   return await runScript(packageName, inMonorepo, 'system-test');
 }
@@ -183,7 +183,7 @@ describe('Run system tests for some libraries', () => {
     });
     await fs.promises.rename(
       path.join(gaxDir, '..', 'tools', toolsBasename),
-      toolsTarball
+      toolsTarball,
     );
     if (!fs.existsSync(toolsTarball)) {
       throw new Error(`npm pack tarball ${toolsTarball} does not exist`);
diff --git a/gax/test/test-application/package.json b/gax/test/test-application/package.json
index dbef3840c..6af31e90d 100644
--- a/gax/test/test-application/package.json
+++ b/gax/test/test-application/package.json
@@ -32,6 +32,6 @@
     "showcase-server": "./showcase-server.tgz"
   },
   "engines": {
-    "node": ">=14.0.0"
+    "node": ">=18.0.0"
   }
 }
diff --git a/gax/test/unit/apiCallable.ts b/gax/test/unit/apiCallable.ts
index 4a17d590b..d31e6c64d 100644
--- a/gax/test/unit/apiCallable.ts
+++ b/gax/test/unit/apiCallable.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {status} from '@grpc/grpc-js';
 import {afterEach, describe, it} from 'mocha';
 import * as sinon from 'sinon';
@@ -34,51 +34,49 @@ describe('createApiCall', () => {
   afterEach(() => {
     sinon.restore();
   });
-  it('calls api call', done => {
+  it('calls api call', async () => {
     let deadlineArg: {};
     function func(
       argument: {},
       metadata: {},
       options: {deadline: string},
-      callback: Function
+      callback: Function,
     ) {
       deadlineArg = options.deadline;
       callback(null, argument);
     }
     const apiCall = createApiCall(func);
-    apiCall(42, undefined, (err, resp) => {
+    await apiCall(42, undefined, (err, resp) => {
       assert.strictEqual(resp, 42);
       assert.ok(deadlineArg);
-      done();
     });
   });
 
-  it('is customized by call options', done => {
+  it('is customized by call options', async () => {
     function func(
       argument: {},
       metadata: {},
       options: {deadline: {getTime: Function}},
-      callback: Function
+      callback: Function,
     ) {
       callback(null, options.deadline.getTime());
     }
     const apiCall = createApiCall(func, {settings: {timeout: 100}});
-    apiCall({}, {timeout: 200}, (err, resp) => {
+    await apiCall({}, {timeout: 200}, (err, resp) => {
       const now = new Date();
       const originalDeadline = now.getTime() + 100;
       const expectedDeadline = now.getTime() + 200;
       assert((resp as unknown as number)! > originalDeadline);
       assert((resp as unknown as number)! <= expectedDeadline);
-      done();
     });
   });
 
-  it('chooses the proper timeout', done => {
+  it('chooses the proper timeout', async () => {
     function func(
       argument: {},
       metadata: {},
       options: {deadline: {getTime: Function}},
-      callback: Function
+      callback: Function,
     ) {
       callback(null, options.deadline.getTime());
     }
@@ -91,28 +89,27 @@ describe('createApiCall', () => {
         timeout: 30000,
         retry: gax.createRetryOptions(
           [],
-          gax.createBackoffSettings(100, 1.2, 1000, 2000, 1.5, 30000, 45000)
+          gax.createBackoffSettings(100, 1.2, 1000, 2000, 1.5, 30000, 45000),
         ),
       },
     });
 
     const start = new Date().getTime();
-    apiCall({}, undefined, (err, resp) => {
+    await apiCall({}, undefined, (err, resp) => {
       // The verifying value is slightly bigger than the expected number
       // 2000 / 30000, because sometimes runtime can consume some time before
       // the call starts.
       assert(Number(resp) - start > 2100);
       assert(Number(resp) - start <= 30100);
-      done();
     });
   });
 
-  it('default to `timeout` for idempotent API calls', done => {
+  it('default to `timeout` for idempotent API calls', async () => {
     function func(
       argument: {},
       metadata: {},
       options: {deadline: {getTime: Function}},
-      callback: Function
+      callback: Function,
     ) {
       callback(null, options.deadline.getTime());
     }
@@ -131,31 +128,25 @@ describe('createApiCall', () => {
     });
 
     const start = new Date().getTime();
-    apiCall({}, undefined, (err, resp) => {
+    await apiCall({}, undefined, (err, resp) => {
       // The verifying value is slightly bigger than the expected number
       // 2000 / 30000, because sometimes runtime can consume some time before
       // the call starts.
       assert(Number(resp) - start > 2100);
       assert(Number(resp) - start <= 30100);
-      done();
     });
   });
-  it('override just custom retry.retryCodes with retry codes', done => {
+  it('override just custom retry.retryCodes with retry codes', () => {
     const initialRetryCodes = [1];
     const overrideRetryCodes = [1, 2, 3];
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     sinon.stub(retries, 'retryable').callsFake((func, retry): any => {
-      try {
-        assert.strictEqual(retry.retryCodes, overrideRetryCodes);
-        return func;
-      } catch (err) {
-        done(err);
-      }
+      assert.strictEqual(retry.retryCodes, overrideRetryCodes);
       return func;
     });
 
     function func() {
-      done();
+      return;
     }
     const apiCall = createApiCall(func, {
       settings: {
@@ -176,8 +167,8 @@ describe('createApiCall', () => {
         retry: {
           retryCodes: overrideRetryCodes,
         },
-      }
-    );
+      },
+    ).catch(console.error);
   });
   it('errors when you override custom retry.shouldRetryFn with a function on a non streaming call', async () => {
     function neverRetry() {
@@ -209,18 +200,18 @@ describe('createApiCall', () => {
           retry: {
             shouldRetryFn: overrideRetryCodes,
           },
-        }
+        },
       );
     } catch (err) {
       assert(err instanceof Error);
       assert.strictEqual(
         err.message,
-        'Using a function to determine retry eligibility is only supported with server streaming calls'
+        'Using a function to determine retry eligibility is only supported with server streaming calls',
       );
     }
   });
 
-  it('override just custom retry.backoffSettings', done => {
+  it('override just custom retry.backoffSettings', () => {
     const initialBackoffSettings = gax.createDefaultBackoffSettings();
     const overriBackoffSettings = gax.createBackoffSettings(
       100,
@@ -229,7 +220,7 @@ describe('createApiCall', () => {
       null,
       1.5,
       3000,
-      4500
+      4500,
     );
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     sinon.stub(retries, 'retryable').callsFake((func, retry): any => {
@@ -238,7 +229,7 @@ describe('createApiCall', () => {
     });
 
     function func() {
-      done();
+      return;
     }
 
     const apiCall = createApiCall(func, {
@@ -253,8 +244,8 @@ describe('createApiCall', () => {
         retry: {
           backoffSettings: overriBackoffSettings,
         },
-      }
-    );
+      },
+    ).catch(console.error);
   });
 
   it('errors when a resumption strategy is passed for a non streaming call', async () => {
@@ -266,7 +257,7 @@ describe('createApiCall', () => {
       null,
       1.5,
       3000,
-      4500
+      4500,
     );
     // "resumption" strategy is to just return the original request
     const getResumptionRequestFn = (originalRequest: RequestType) => {
@@ -274,7 +265,7 @@ describe('createApiCall', () => {
     };
 
     function func() {
-      Promise.resolve();
+      Promise.resolve().catch(console.error);
     }
     const apiCall = createApiCall(func, {
       settings: {
@@ -282,7 +273,7 @@ describe('createApiCall', () => {
           [1],
           initialBackoffSettings,
           undefined,
-          getResumptionRequestFn
+          getResumptionRequestFn,
         ),
       },
     });
@@ -294,13 +285,13 @@ describe('createApiCall', () => {
           retry: {
             backoffSettings: overriBackoffSettings,
           },
-        }
+        },
       );
     } catch (err) {
       assert(err instanceof Error);
       assert.strictEqual(
         err.message,
-        'Resumption strategy can only be used with server streaming retries'
+        'Resumption strategy can only be used with server streaming retries',
       );
     }
   });
@@ -313,7 +304,7 @@ describe('Promise', () => {
       argument: {},
       metadata: {},
       options: {deadline: string},
-      callback: Function
+      callback: Function,
     ) {
       deadlineArg = options.deadline;
       callback(null, 42);
@@ -418,7 +409,7 @@ describe('Promise', () => {
         assert.strictEqual(response, 42);
         done();
       }),
-      undefined
+      undefined,
     );
   });
 });
@@ -429,14 +420,14 @@ describe('retryable', () => {
     settings: {timeout: 0, retry: retryOptions, apiName: 'TestApi'},
   };
 
-  it('retries the API call', done => {
+  it('retries the API call', async () => {
     let toAttempt = 3;
     let deadlineArg: string;
     function func(
       argument: {},
       metadata: {},
       options: {deadline: string},
-      callback: Function
+      callback: Function,
     ) {
       deadlineArg = options.deadline;
       toAttempt--;
@@ -447,22 +438,21 @@ describe('retryable', () => {
       callback(null, 1729);
     }
     const apiCall = createApiCall(func, settings);
-    apiCall({}, undefined, (err, resp) => {
+    await apiCall({}, undefined, (err, resp) => {
       assert.strictEqual(resp, 1729);
       assert.strictEqual(toAttempt, 0);
       assert(deadlineArg);
-      done();
     });
   });
 
-  it('retries the API call with promise', done => {
+  it('retries the API call with promise', async () => {
     let toAttempt = 3;
     let deadlineArg: string;
     function func(
       argument: {},
       metadata: {},
       options: {deadline: string},
-      callback: Function
+      callback: Function,
     ) {
       deadlineArg = options.deadline;
       toAttempt--;
@@ -473,15 +463,12 @@ describe('retryable', () => {
       callback(null, 1729);
     }
     const apiCall = createApiCall(func, settings);
-    apiCall({}, undefined)
-      .then(resp => {
-        assert.ok(Array.isArray(resp));
-        assert.strictEqual(resp[0], 1729);
-        assert.strictEqual(toAttempt, 0);
-        assert.ok(deadlineArg);
-        done();
-      })
-      .catch(done);
+    await apiCall({}, undefined).then(resp => {
+      assert.ok(Array.isArray(resp));
+      assert.strictEqual(resp[0], 1729);
+      assert.strictEqual(toAttempt, 0);
+      assert.ok(deadlineArg);
+    });
   });
 
   it('cancels in the middle of retries', done => {
@@ -512,29 +499,27 @@ describe('retryable', () => {
       });
   });
 
-  it("doesn't retry if no codes", done => {
+  it("doesn't retry if no codes", async () => {
     const retryOptions = gax.createRetryOptions(
       [],
-      gax.createBackoffSettings(1, 2, 3, 4, 5, 6, 7)
+      gax.createBackoffSettings(1, 2, 3, 4, 5, 6, 7),
     );
     const settings = {settings: {timeout: 0, retry: retryOptions}};
     const spy = sinon.spy(fail);
     const apiCall = createApiCall(spy, settings);
-    apiCall({}, undefined, err => {
+    await apiCall({}, undefined, err => {
       assert.ok(err instanceof Error);
       assert.strictEqual(err!.code, FAKE_STATUS_CODE_1);
       assert.strictEqual(err!.note, undefined);
       assert.strictEqual(spy.callCount, 1);
-      done();
     });
   });
 
-  it('aborts retries', done => {
+  it('aborts retries', async () => {
     const apiCall = createApiCall(fail, settings);
-    apiCall({}, undefined, err => {
+    await apiCall({}, undefined, err => {
       assert(err instanceof GoogleError);
       assert.strictEqual(err!.code, status.DEADLINE_EXCEEDED);
-      done();
     });
   });
 
@@ -548,10 +533,10 @@ describe('retryable', () => {
       assert(err!.note);
       assert.strictEqual(spy.callCount, toAttempt);
       done();
-    });
+    }).catch(console.error);
   });
 
-  it('errors on maxRetries and surfaces original error', done => {
+  it('errors on maxRetries and surfaces original error', async () => {
     const toAttempt = 5;
     const backoff = gax.createMaxRetriesBackoffSettings(
       0,
@@ -560,7 +545,7 @@ describe('retryable', () => {
       0,
       0,
       0,
-      toAttempt
+      toAttempt,
     );
     const maxRetriesRetryOptions = utils.createRetryOptions(backoff);
 
@@ -569,35 +554,33 @@ describe('retryable', () => {
     };
     const spy = sinon.spy(fail);
     const apiCall = createApiCall(spy, maxRetrySettings);
-    apiCall({}, undefined, err => {
+    await apiCall({}, undefined, err => {
       assert.ok(err instanceof GoogleError);
       assert.strictEqual(err!.code, status.DEADLINE_EXCEEDED);
       assert.strictEqual(spy.callCount, toAttempt);
       assert.match(
         err.message,
-        /Exceeded maximum number of retries retrying error Error before any response was received/
+        /Exceeded maximum number of retries retrying error Error before any response was received/,
       );
-      done();
     });
   });
 
-  it('retry fails for exceeding total timeout, surfacing original error', done => {
+  it('retry fails for exceeding total timeout, surfacing original error', async () => {
     const spy = sinon.spy(fail);
     const apiCall = createApiCall(spy, settings);
-    apiCall({}, undefined, err => {
+    await apiCall({}, undefined, err => {
       assert.ok(err instanceof GoogleError);
       assert.match(
         err.message,
-        /Total timeout of API TestApi exceeded 100 milliseconds retrying error Error {2}before any response was received/
+        /Total timeout of API TestApi exceeded 100 milliseconds retrying error Error {2}before any response was received/,
       );
       assert.strictEqual(err!.code, status.DEADLINE_EXCEEDED);
-      done();
     });
   });
 
   // maxRetries is unsupported, and intended for internal use only or
   // use with retry-request backwards compatibility
-  it('errors when totalTimeoutMillis and maxRetries set', done => {
+  it('errors when totalTimeoutMillis and maxRetries set', async () => {
     const maxRetries = 5;
     const backoff = gax.createMaxRetriesBackoffSettings(
       0,
@@ -606,7 +589,7 @@ describe('retryable', () => {
       0,
       0,
       0,
-      maxRetries
+      maxRetries,
     );
     const maxRetriesRetryOptions = utils.createRetryOptions(backoff);
     maxRetriesRetryOptions.backoffSettings.totalTimeoutMillis = 100;
@@ -615,15 +598,14 @@ describe('retryable', () => {
     };
     const spy = sinon.spy(fail);
     const apiCall = createApiCall(spy, maxRetrySettings);
-    apiCall({}, undefined, err => {
+    await apiCall({}, undefined, err => {
       assert(err instanceof GoogleError);
       assert.strictEqual(err!.code, status.INVALID_ARGUMENT);
       assert.strictEqual(spy.callCount, 0);
-      done();
     });
   });
 
-  it('aborts on unexpected exception', done => {
+  it('aborts on unexpected exception', async () => {
     function func(argument: {}, metadata: {}, options: {}, callback: Function) {
       const error = new GoogleError();
       error.code = FAKE_STATUS_CODE_2;
@@ -631,24 +613,22 @@ describe('retryable', () => {
     }
     const spy = sinon.spy(func);
     const apiCall = createApiCall(spy, settings);
-    apiCall({}, undefined, err => {
+    await apiCall({}, undefined, err => {
       assert(err instanceof Error);
       assert.strictEqual(err!.code, FAKE_STATUS_CODE_2);
       assert(err!.note);
       assert.strictEqual(spy.callCount, 1);
-      done();
     });
   });
 
-  it('does not retry even when no responses', done => {
+  it('does not retry even when no responses', async () => {
     function func(argument: {}, metadata: {}, options: {}, callback: Function) {
       callback(null, null);
     }
     const apiCall = createApiCall(func, settings);
-    apiCall({}, undefined, (err, resp) => {
+    await apiCall({}, undefined, (err, resp) => {
       assert.strictEqual(err, null);
       assert.strictEqual(resp, null);
-      done();
     });
   });
 
@@ -668,7 +648,7 @@ describe('retryable', () => {
       assert(err!.note);
       const now = new Date();
       assert(
-        now.getTime() - startTime.getTime() >= backoff.totalTimeoutMillis!
+        now.getTime() - startTime.getTime() >= backoff.totalTimeoutMillis!,
       );
       const callsLowerBound =
         backoff.totalTimeoutMillis! /
@@ -678,7 +658,7 @@ describe('retryable', () => {
       assert(spy.callCount > callsLowerBound);
       assert(spy.callCount < callsUpperBound);
       done();
-    });
+    }).catch(console.error);
   });
 
   it.skip('reports A/B testing', () => {
@@ -706,7 +686,7 @@ describe('retryable', () => {
           0,
           0,
           0,
-          5
+          5,
         );
         mockBuilder.withExactArgs({retry: '1'});
         return apiCall({}, {retry: utils.createRetryOptions(backoff)});
@@ -725,7 +705,7 @@ describe('retryable', () => {
       });
   });
 
-  it('forwards metadata to builder', done => {
+  it('forwards metadata to builder', async () => {
     function func(argument: {}, metadata: {}, options: {}, callback: Function) {
       callback(null, {});
     }
@@ -744,10 +724,9 @@ describe('retryable', () => {
       h1: 'val1',
       h2: 'val2',
     };
-    apiCall({}, {otherArgs: {headers}}).then(() => {
+    await apiCall({}, {otherArgs: {headers}}).then(() => {
       assert.strictEqual(gotHeaders.h1, 'val1');
       assert.strictEqual(gotHeaders.h2, 'val2');
-      done();
     });
   });
 });
diff --git a/gax/test/unit/bundling.ts b/gax/test/unit/bundling.ts
index d757d311b..ac16ae0b6 100644
--- a/gax/test/unit/bundling.ts
+++ b/gax/test/unit/bundling.ts
@@ -17,7 +17,7 @@
 /* eslint-disable @typescript-eslint/ban-ts-comment */
 /* eslint-disable no-prototype-builtins */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {status} from '@grpc/grpc-js';
 import * as sinon from 'sinon';
 import {describe, it, beforeEach} from 'mocha';
@@ -107,7 +107,7 @@ describe('computeBundleId', () => {
       it(t.message, () => {
         assert.strictEqual(
           computeBundleId(t.object as unknown as RequestType, t.fields),
-          t.want
+          t.want,
         );
       });
     });
@@ -215,7 +215,7 @@ describe('Task', () => {
     task: any,
     elements: string[] | number[],
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    callback?: any
+    callback?: any,
   ) {
     if (!callback) {
       callback = () => {};
@@ -256,7 +256,7 @@ describe('Task', () => {
           assert.strictEqual(
             task.getElementCount(),
             baseCount! + t.want,
-            t.message
+            t.message,
           );
         });
       });
@@ -271,7 +271,7 @@ describe('Task', () => {
           extendElements(task, t.data);
           assert.strictEqual(
             task.getRequestByteSize(),
-            baseSize! + t.want * sizePerData
+            baseSize! + t.want * sizePerData,
           );
         });
       });
@@ -511,7 +511,7 @@ describe('Executor', () => {
       'field1',
       ['field2'],
       'field1',
-      byteLength
+      byteLength,
     );
     return new BundleExecutor(options, descriptor);
   }
@@ -636,9 +636,9 @@ describe('Executor', () => {
               assert.deepStrictEqual(resp.field1, [3, 4]);
               assert.strictEqual(spyApi.callCount, 1);
               done();
-            }
+            },
           );
-        }
+        },
       );
       assert.strictEqual(spyApi.callCount, 0);
       canceller.cancel();
@@ -750,7 +750,7 @@ describe('Executor', () => {
         assert(err instanceof GoogleError);
         assert.strictEqual(err!.code, status.INVALID_ARGUMENT);
         done();
-      }
+      },
     );
   });
 
@@ -787,7 +787,7 @@ describe('Executor', () => {
         assert(err instanceof GoogleError);
         assert.strictEqual(err!.code, status.INVALID_ARGUMENT);
         done();
-      }
+      },
     );
   });
 
@@ -862,34 +862,31 @@ describe('bundleable', () => {
     'field1',
     ['field2'],
     'field1',
-    byteLength
+    byteLength,
   );
   const settings = {
     settings: {bundleOptions},
     descriptor,
   };
 
-  it('bundles requests', done => {
+  it('bundles requests', async () => {
     const spy = sinon.spy(func);
     const callback = sinon.spy(obj => {
       assert(Array.isArray(obj));
       assert.deepStrictEqual(obj[0].field1, [1, 2, 3]);
       if (callback.callCount === 2) {
         assert.strictEqual(spy.callCount, 1);
-        done();
       }
     });
     const apiCall = createApiCall(spy, settings);
-    apiCall({field1: [1, 2, 3], field2: 'id'}, undefined, (err, obj) => {
+    await apiCall({field1: [1, 2, 3], field2: 'id'}, undefined, (err, obj) => {
       if (err) {
-        done(err);
+        throw err;
       } else {
         callback([obj]);
       }
     });
-    apiCall({field1: [1, 2, 3], field2: 'id'}, undefined)
-      .then(callback)
-      .catch(done);
+    await apiCall({field1: [1, 2, 3], field2: 'id'}, undefined).then(callback);
   });
 
   it('does not fail if bundle field is not set', done => {
@@ -978,12 +975,12 @@ describe('bundleable', () => {
     p.cancel();
   });
 
-  it('properly processes camel case fields', done => {
+  it('properly processes camel case fields', async () => {
     const descriptor = new BundleDescriptor(
       'data',
       ['log_name'],
       'data',
-      byteLength
+      byteLength,
     );
     const settings = {
       settings: {bundleOptions},
@@ -993,34 +990,33 @@ describe('bundleable', () => {
     const callback = sinon.spy(() => {
       if (callback.callCount === 4) {
         assert.strictEqual(spy.callCount, 2); // we expect two requests, each has two items
-        done();
       }
     });
     const apiCall = createApiCall(spy, settings);
-    apiCall({data: ['data1'], logName: 'log1'}, undefined, err => {
+    await apiCall({data: ['data1'], logName: 'log1'}, undefined, err => {
       if (err) {
-        done(err);
+        throw err;
       } else {
         callback();
       }
     });
-    apiCall({data: ['data1'], logName: 'log2'}, undefined, err => {
+    await apiCall({data: ['data1'], logName: 'log2'}, undefined, err => {
       if (err) {
-        done(err);
+        throw err;
       } else {
         callback();
       }
     });
-    apiCall({data: ['data2'], logName: 'log1'}, undefined, err => {
+    await apiCall({data: ['data2'], logName: 'log1'}, undefined, err => {
       if (err) {
-        done(err);
+        throw err;
       } else {
         callback();
       }
     });
-    apiCall({data: ['data2'], logName: 'log2'}, undefined, err => {
+    await apiCall({data: ['data2'], logName: 'log2'}, undefined, err => {
       if (err) {
-        done(err);
+        throw err;
       } else {
         callback();
       }
diff --git a/gax/test/unit/exports.ts b/gax/test/unit/exports.ts
index 032ddc574..8132209b4 100644
--- a/gax/test/unit/exports.ts
+++ b/gax/test/unit/exports.ts
@@ -16,7 +16,7 @@
 
 import * as index from '../../src/index';
 import * as fallback from '../../src/fallback';
-import * as assert from 'assert';
+import assert from 'assert';
 import {describe, it} from 'mocha';
 
 const version = require('../../../package.json').version;
diff --git a/gax/test/unit/fallbackError.ts b/gax/test/unit/fallbackError.ts
index de8ba72b1..ad2479a55 100644
--- a/gax/test/unit/fallbackError.ts
+++ b/gax/test/unit/fallbackError.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {describe, it} from 'mocha';
 import * as fs from 'fs';
 import * as path from 'path';
@@ -46,7 +46,7 @@ describe('gRPC-fallback error decoding', () => {
     assert.strictEqual(decodedError.message, expectedError.message);
     assert.strictEqual(
       JSON.stringify(decodedError.statusDetails),
-      JSON.stringify(expectedError.details)
+      JSON.stringify(expectedError.details),
     );
   });
 
@@ -56,7 +56,7 @@ describe('gRPC-fallback error decoding', () => {
     const errorBin = fs.readFileSync(fixtureName);
     const expectedError = Object.assign(
       new Error(
-        '3 INVALID_ARGUMENT: One of content, or gcs_content_uri must be set.'
+        '3 INVALID_ARGUMENT: One of content, or gcs_content_uri must be set.',
       ),
       {
         code: 3,
@@ -70,7 +70,7 @@ describe('gRPC-fallback error decoding', () => {
             ],
           },
         ],
-      }
+      },
     );
     const decoder = new GoogleErrorDecoder();
     const decodedError = decoder.decodeErrorFromBuffer(errorBin);
@@ -80,7 +80,7 @@ describe('gRPC-fallback error decoding', () => {
     assert.strictEqual(decodedError.message, expectedError.message);
     assert.strictEqual(
       JSON.stringify(decodedError.statusDetails),
-      JSON.stringify(expectedError.details)
+      JSON.stringify(expectedError.details),
     );
   });
 
@@ -91,7 +91,7 @@ describe('gRPC-fallback error decoding', () => {
       '..',
       'protos',
       'google',
-      'rpc'
+      'rpc',
     );
     const root = protobuf.loadSync([
       path.join(protos_path, 'error_details.proto'),
@@ -115,7 +115,7 @@ describe('gRPC-fallback error decoding', () => {
         reason: errorInfo.reason,
         domain: errorInfo.domain,
         errorInfoMetadata: errorInfo.metadata,
-      }
+      },
     );
     const status = Object.assign(new Error('mock error.'), {
       code: 7,
@@ -134,7 +134,7 @@ describe('gRPC-fallback error decoding', () => {
     assert.strictEqual(decodedError.message, expectedError.message);
     assert.strictEqual(
       JSON.stringify(decodedError.statusDetails),
-      JSON.stringify(expectedError.details)
+      JSON.stringify(expectedError.details),
     );
   });
 });
diff --git a/gax/test/unit/gax.ts b/gax/test/unit/gax.ts
index 846dd51a0..214b3d07d 100644
--- a/gax/test/unit/gax.ts
+++ b/gax/test/unit/gax.ts
@@ -22,7 +22,7 @@
 
 /* eslint-disable @typescript-eslint/ban-ts-comment */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {describe, it} from 'mocha';
 import * as gax from '../../src/gax';
 
@@ -76,7 +76,7 @@ function expectRetryOptions(obj: gax.RetryOptions) {
   assert.ok(obj instanceof Object);
   ['retryCodes', 'backoffSettings'].forEach(k =>
     // eslint-disable-next-line no-prototype-builtins
-    assert.ok(obj.hasOwnProperty(k))
+    assert.ok(obj.hasOwnProperty(k)),
   );
   assert.ok(Array.isArray(obj.retryCodes));
   expectBackoffSettings(obj.backoffSettings);
@@ -106,7 +106,7 @@ describe('gax construct settings', () => {
       A_CONFIG,
       {},
       RETRY_DICT,
-      otherArgs
+      otherArgs,
     );
     let settings = defaults.bundlingMethod;
     assert.strictEqual(settings.timeout, 40000);
@@ -137,7 +137,7 @@ describe('gax construct settings', () => {
       SERVICE_NAME,
       A_CONFIG,
       overrides,
-      RETRY_DICT
+      RETRY_DICT,
     );
     let settings = defaults.bundlingMethod;
     assert.strictEqual(settings.timeout, 40000);
@@ -179,7 +179,7 @@ describe('gax construct settings', () => {
       SERVICE_NAME,
       A_CONFIG,
       overrides,
-      RETRY_DICT
+      RETRY_DICT,
     );
 
     let settings = defaults.bundlingMethod;
diff --git a/gax/test/unit/googleError.ts b/gax/test/unit/googleError.ts
index a4bc7bd1d..47b8a8523 100644
--- a/gax/test/unit/googleError.ts
+++ b/gax/test/unit/googleError.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {describe, it} from 'mocha';
 import * as fs from 'fs';
 import * as util from 'util';
@@ -34,7 +34,7 @@ describe('gRPC-google error decoding', () => {
     __dirname,
     '..',
     'fixtures',
-    'multipleErrors.json'
+    'multipleErrors.json',
   );
   const protos_path = path.resolve(
     __dirname,
@@ -42,7 +42,7 @@ describe('gRPC-google error decoding', () => {
     '..',
     'protos',
     'google',
-    'rpc'
+    'rpc',
   );
   const root = protobuf.loadSync([
     path.join(protos_path, 'error_details.proto'),
@@ -72,17 +72,17 @@ describe('gRPC-google error decoding', () => {
     const Status = root.lookupType('google.rpc.Status');
     const statusBuffer = Status.encode(status).finish() as Buffer;
     const gRPCStatusDetailsObj = decoder.decodeGRPCStatusDetails(
-      new Array(statusBuffer)
+      new Array(statusBuffer),
     );
     assert.strictEqual(
       JSON.stringify(expectedErrorArr),
-      JSON.stringify(gRPCStatusDetailsObj.details)
+      JSON.stringify(gRPCStatusDetailsObj.details),
     );
     assert.deepStrictEqual(
       JSON.stringify(gRPCStatusDetailsObj.errorInfo),
       JSON.stringify(
-        objs.find(item => item.type === 'google.rpc.ErrorInfo')?.value
-      )
+        objs.find(item => item.type === 'google.rpc.ErrorInfo')?.value,
+      ),
     );
   });
 
@@ -96,7 +96,7 @@ describe('gRPC-google error decoding', () => {
     // nested error messages have different types so we can't use deepStrictEqual here
     assert.strictEqual(
       JSON.stringify(gRPCStatusDetailsObj.details),
-      JSON.stringify([])
+      JSON.stringify([]),
     );
     assert.strictEqual(gRPCStatusDetailsObj.errorInfo, undefined);
   });
@@ -112,7 +112,7 @@ describe('gRPC-google error decoding', () => {
 
     assert.strictEqual(
       JSON.stringify(decodedError),
-      '{"code":3,"message":"test","statusDetails":[]}'
+      '{"code":3,"message":"test","statusDetails":[]}',
     );
   });
 
@@ -129,7 +129,7 @@ describe('gRPC-google error decoding', () => {
 
     assert.strictEqual(
       JSON.stringify(gRPCStatusDetailsObj.details),
-      JSON.stringify([])
+      JSON.stringify([]),
     );
   });
 
@@ -146,7 +146,7 @@ describe('gRPC-google error decoding', () => {
         0,
         err
           .toString()
-          .indexOf('Error: Unknown type encoded in google.protobuf.any:')
+          .indexOf('Error: Unknown type encoded in google.protobuf.any:'),
       );
     }
   });
@@ -197,7 +197,7 @@ describe('parse grpc status details with ErrorInfo from grpc metadata', () => {
       {
         code: 7,
         metadata: metadata,
-      }
+      },
     );
     const decodedError = GoogleError.parseGRPCStatusDetails(grpcError);
     assert(decodedError instanceof GoogleError);
@@ -205,7 +205,7 @@ describe('parse grpc status details with ErrorInfo from grpc metadata', () => {
     assert.strictEqual(decodedError.reason, errorInfoObj.reason);
     assert.strictEqual(
       JSON.stringify(decodedError.errorInfoMetadata),
-      JSON.stringify(errorInfoObj.metadata)
+      JSON.stringify(errorInfoObj.metadata),
     );
   });
 
@@ -233,19 +233,19 @@ describe('parse grpc status details with ErrorInfo from grpc metadata', () => {
       {
         code: 7,
         metadata: metadata,
-      }
+      },
     );
     const decodedError = GoogleError.parseGRPCStatusDetails(grpcError);
     assert(decodedError instanceof GoogleError);
     assert.strictEqual(
       JSON.stringify(decodedError.statusDetails),
-      JSON.stringify([errorInfoObj])
+      JSON.stringify([errorInfoObj]),
     );
     assert.strictEqual(decodedError.domain, errorInfoObj.domain);
     assert.strictEqual(decodedError.reason, errorInfoObj.reason);
     assert.strictEqual(
       JSON.stringify(decodedError.errorInfoMetadata),
-      JSON.stringify(errorInfoObj.metadata)
+      JSON.stringify(errorInfoObj.metadata),
     );
   });
 
@@ -257,7 +257,7 @@ describe('parse grpc status details with ErrorInfo from grpc metadata', () => {
       {
         code: 7,
         metadata: metadata,
-      }
+      },
     );
     const decodedError = GoogleError.parseGRPCStatusDetails(grpcError);
     assert(decodedError instanceof GoogleError);
@@ -269,7 +269,7 @@ describe('parse grpc status details with ErrorInfo from grpc metadata', () => {
       new GoogleError('mock error without metadata'),
       {
         code: 7,
-      }
+      },
     );
     const decodedError = GoogleError.parseGRPCStatusDetails(grpcError);
     assert(decodedError instanceof GoogleError);
@@ -319,7 +319,7 @@ describe('map http status code to gRPC status code', () => {
       },
     };
     const errorAlreadyExists = GoogleError.parseHttpError(
-      errorJsonAlreadyExistss
+      errorJsonAlreadyExistss,
     );
     assert.deepStrictEqual(errorAborted.code, Status.ABORTED);
     assert.deepStrictEqual(errorAlreadyExists.code, Status.ALREADY_EXISTS);
@@ -359,14 +359,14 @@ describe('http error decoding', () => {
     assert.deepStrictEqual(error.code, rpcCodeFromHttpStatusCode(403));
     assert.deepStrictEqual(
       error.statusDetails?.length,
-      json['error']['details'].length
+      json['error']['details'].length,
     );
     assert.deepStrictEqual(error.message, json['error']['message']);
     assert.deepStrictEqual(error.reason, errorInfo.reason);
     assert.deepStrictEqual(error.domain, errorInfo.domain);
     assert.deepStrictEqual(
       JSON.stringify(error.errorInfoMetadata),
-      JSON.stringify(errorInfo.metadata)
+      JSON.stringify(errorInfo.metadata),
     );
   });
 
@@ -375,14 +375,14 @@ describe('http error decoding', () => {
     assert.deepStrictEqual(error.code, rpcCodeFromHttpStatusCode(403));
     assert.deepStrictEqual(
       error.statusDetails?.length,
-      json['error']['details'].length
+      json['error']['details'].length,
     );
     assert.deepStrictEqual(error.message, json['error']['message']);
     assert.deepStrictEqual(error.reason, errorInfo.reason);
     assert.deepStrictEqual(error.domain, errorInfo.domain);
     assert.deepStrictEqual(
       JSON.stringify(error.errorInfoMetadata),
-      JSON.stringify(errorInfo.metadata)
+      JSON.stringify(errorInfo.metadata),
     );
   });
 });
diff --git a/gax/test/unit/grpc-fallback.ts b/gax/test/unit/grpc-fallback.ts
index 0c3c94952..f12fc3801 100644
--- a/gax/test/unit/grpc-fallback.ts
+++ b/gax/test/unit/grpc-fallback.ts
@@ -17,15 +17,15 @@
 /* eslint-disable @typescript-eslint/ban-ts-comment */
 /* eslint-disable no-undef */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {describe, it, beforeEach, afterEach, before, after} from 'mocha';
-import * as nodeFetch from 'node-fetch';
 import * as abortController from 'abort-controller';
 import * as protobuf from 'protobufjs';
 import * as sinon from 'sinon';
 import echoProtoJson = require('../fixtures/echo.json');
 import {GrpcClient} from '../../src/fallback';
 import {GoogleError} from '../../src';
+import proxyquire from 'proxyquire';
 
 // @ts-ignore
 const hasAbortController = typeof AbortController !== 'undefined';
@@ -138,18 +138,22 @@ describe('createStub', () => {
 
   it('validates universe domain if set', async () => {
     const opts = {...stubOptions, universeDomain: 'example.com'};
-    assert.rejects(
-      gaxGrpc.createStub(echoService, opts),
-      /configured universe domain/
-    );
+    assert
+      .rejects(
+        gaxGrpc.createStub(echoService, opts),
+        /configured universe domain/,
+      )
+      .catch(console.error);
   });
 
   it('validates universe domain if unset', async () => {
     authClient.universeDomain = 'example.com';
-    assert.rejects(
-      gaxGrpc.createStub(echoService, stubOptions),
-      /configured universe domain/
-    );
+    assert
+      .rejects(
+        gaxGrpc.createStub(echoService, stubOptions),
+        /configured universe domain/,
+      )
+      .catch(console.error);
     // reset to default value
     authClient.universeDomain = 'googleapis.com';
   });
@@ -209,6 +213,7 @@ describe('grpc-fallback', () => {
 
     if (hasAbortController) {
       // @ts-ignore
+      // eslint-disable-next-line no-global-assign
       AbortController = FakeAbortController;
     } else {
       // @ts-ignore
@@ -227,6 +232,7 @@ describe('grpc-fallback', () => {
   after(() => {
     if (hasAbortController) {
       // @ts-ignore
+      // eslint-disable-next-line no-global-assign
       AbortController = savedAbortController;
     } else {
       // @ts-ignore
@@ -268,40 +274,43 @@ describe('grpc-fallback', () => {
       'google.showcase.v1beta1.Echo',
       gapicConfig,
       {},
-      {}
+      {},
     );
     const metadataBuilder = settings.echo.otherArgs.metadataBuilder;
     const headers = metadataBuilder();
     assert(headers['x-goog-api-client'][0].match('grpc-web/'));
   });
-
-  it('should make a request', done => {
+  it('should make a request', async () => {
     const requestObject = {content: 'test-content'};
     const responseType = protos.lookupType('EchoResponse');
     const response = responseType.create(requestObject); // request === response for EchoService
-    //@ts-ignore
-    sinon.stub(nodeFetch, 'Promise').returns(
-      Promise.resolve({
-        ok: true,
-        arrayBuffer: () => {
-          return Promise.resolve(Buffer.from(JSON.stringify(response)));
-        },
-      })
-    );
 
-    gaxGrpc.createStub(echoService, stubOptions).then(echoStub => {
-      echoStub.echo(requestObject, {}, {}, (err?: Error, result?: {}) => {
-        assert.strictEqual(err, null);
-        assert.strictEqual(
-          requestObject.content,
-          (result as {content: string}).content
-        );
-        done();
-      });
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.resolve({
+          ok: true,
+          arrayBuffer: () => {
+            return Promise.resolve(Buffer.from(JSON.stringify(response)));
+          },
+        });
+      },
     });
+
+    const gaxGrpcMock = new GrpcClient();
+    gaxGrpcMock
+      .createStub(echoService, stubOptions)
+      .then((echoStub: {echo: any}) => {
+        echoStub.echo(requestObject, {}, {}, (err?: Error, result?: {}) => {
+          assert.strictEqual(err, null);
+          assert.strictEqual(
+            requestObject.content,
+            (result as {content: string}).content,
+          );
+        });
+      });
   });
 
-  it('should handle an API error', done => {
+  it('should handle an API error', async () => {
     const requestObject = {content: 'test-content'};
     // example of an actual google.rpc.Status error message returned by Language API
     const expectedMessage =
@@ -334,63 +343,51 @@ describe('grpc-fallback', () => {
         },
       ],
     };
-    //@ts-ignore
-    sinon.stub(nodeFetch, 'Promise').returns(
-      Promise.resolve({
-        ok: false,
-        arrayBuffer: () => {
-          return Promise.resolve(Buffer.from(JSON.stringify(jsonError)));
-        },
-      })
-    );
-    gaxGrpc.createStub(echoService, stubOptions).then(echoStub => {
+
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.resolve({
+          ok: true,
+          arrayBuffer: () => {
+            return Promise.resolve(Buffer.from(JSON.stringify(jsonError)));
+          },
+        });
+      },
+    });
+
+    const gaxGrpcMock = new GrpcClient();
+
+    gaxGrpcMock.createStub(echoService, stubOptions).then((echoStub: any) => {
       echoStub.echo(requestObject, {}, {}, (err?: Error) => {
         assert(err instanceof GoogleError);
         assert.strictEqual(err.message, expectedMessage);
         assert.strictEqual(err.code, expectedError.code);
         assert.strictEqual(
           JSON.stringify(err.statusDetails),
-          JSON.stringify(expectedError.details)
+          JSON.stringify(expectedError.details),
         );
-        done();
       });
     });
   });
-  it('should handle a null response from the API ', done => {
+
+  it('should handle a fetch error', async () => {
     const requestObject = {content: 'test-content'};
-    const expectedMessage = 'Received null response from RPC Echo';
-
-    //@ts-ignore
-    sinon.stub(nodeFetch, 'Promise').returns(
-      Promise.resolve({
-        ok: false,
-        arrayBuffer: () => {
-          return Promise.resolve(Buffer.from(''));
-        },
-      })
-    );
-    gaxGrpc.createStub(echoService, stubOptions).then(echoStub => {
-      echoStub.echo(requestObject, {}, {}, (err?: Error) => {
-        assert(err instanceof Error);
-        assert.strictEqual(err.message, expectedMessage);
-        done();
-      });
+
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.reject(new Error('fetch error'));
+      },
     });
-  });
 
-  it('should handle a fetch error', done => {
-    const requestObject = {content: 'test-content'};
-    //@ts-ignore
-    sinon.stub(nodeFetch, 'Promise').rejects(new Error('fetch error'));
-    gaxGrpc.createStub(echoService, stubOptions).then(echoStub => {
+    const gaxGrpcMock = new GrpcClient();
+    gaxGrpcMock.createStub(echoService, stubOptions).then((echoStub: any) => {
       echoStub.echo(requestObject, {}, {}, (err?: Error) => {
         assert.strictEqual(err?.message, 'fetch error');
-        done();
       });
     });
   });
 
-  it('should promote ErrorInfo if exist in fallback-rest error', done => {
+  it('should promote ErrorInfo if exist in fallback-rest error', async () => {
     const requestObject = {content: 'test-content'};
     // example of an actual google.rpc.Status error message returned by Translate API
     const errorInfo = {
@@ -426,23 +423,26 @@ describe('grpc-fallback', () => {
       auth: authStub,
       fallback: 'rest',
     };
-    // @ts-ignore incomplete options
-    gaxGrpc = new GrpcClient(opts);
-    //@ts-ignore
-    sinon.stub(nodeFetch, 'Promise').returns(
-      Promise.resolve({
-        ok: false,
-        arrayBuffer: () => {
-          return Promise.resolve(Buffer.from(JSON.stringify(serverError)));
-        },
-      })
-    );
-    gaxGrpc.createStub(echoService, stubOptions).then(echoStub => {
+
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.resolve({
+          ok: true,
+          arrayBuffer: () => {
+            return Promise.resolve(Buffer.from(JSON.stringify(serverError)));
+          },
+        });
+      },
+    });
+
+    const gaxGrpcMock = new GrpcClient(opts);
+
+    gaxGrpcMock.createStub(echoService, stubOptions).then((echoStub: any) => {
       echoStub.echo(requestObject, {}, {}, (err?: Error) => {
         assert(err instanceof GoogleError);
         assert.strictEqual(
           JSON.stringify(err.statusDetails?.length),
-          JSON.stringify(serverError['error']['details'].length)
+          JSON.stringify(serverError['error']['details'].length),
         );
         assert.strictEqual(err.code, 7);
         assert.strictEqual(err.message, serverError['error']['message']);
@@ -450,33 +450,56 @@ describe('grpc-fallback', () => {
         assert.strictEqual(err.domain, errorInfo.domain);
         assert.strictEqual(
           JSON.stringify(err.errorInfoMetadata),
-          JSON.stringify(errorInfo.metadata)
+          JSON.stringify(errorInfo.metadata),
         );
-        done();
       });
     });
   });
 
   it('should be able to cancel an API call using AbortController', async () => {
-    // @ts-ignore
-    sinon.stub(nodeFetch, 'Promise').returns(Promise.resolve({}));
+    const opts = {
+      auth: authStub,
+      fallback: 'rest',
+    };
+
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.resolve({
+          ok: true,
+          arrayBuffer: () => {
+            return Promise.resolve(Buffer.from(JSON.stringify({})));
+          },
+        });
+      },
+    });
+
+    const gaxGrpcMock = new GrpcClient(opts);
+    const echoStub = await gaxGrpcMock.createStub(echoService, stubOptions);
 
-    const echoStub = await gaxGrpc.createStub(echoService, stubOptions);
     const request = {content: 'content' + new Date().toString()};
     const call = echoStub.echo(request, {}, {}, () => {});
 
     call.cancel();
 
-    // @ts-ignore
-    assert.strictEqual(createdAbortControllers[0].abortCalled, true);
+    assert.strictEqual((createdAbortControllers[0] as any).abortCalled, true);
   });
 
-  it('should have close method', done => {
-    // @ts-ignore
-    sinon.stub(nodeFetch, 'Promise').returns(Promise.resolve({}));
-    gaxGrpc.createStub(echoService, stubOptions).then(stub => {
+  it('should have close method', async () => {
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.resolve({
+          ok: true,
+          arrayBuffer: () => {
+            return Promise.resolve({});
+          },
+        });
+      },
+    });
+
+    const gaxGrpcMock = new GrpcClient();
+
+    gaxGrpcMock.createStub(echoService, stubOptions).then((stub: any) => {
       stub.close({}, {}, {}, () => {});
-      done();
     });
   });
 });
diff --git a/gax/test/unit/grpc.ts b/gax/test/unit/grpc.ts
index 084daeb75..6d5de2f7f 100644
--- a/gax/test/unit/grpc.ts
+++ b/gax/test/unit/grpc.ts
@@ -18,10 +18,10 @@
 /* eslint-disable no-prototype-builtins */
 /* eslint-disable @typescript-eslint/no-var-requires */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import * as os from 'os';
 import * as path from 'path';
-import * as proxyquire from 'proxyquire';
+import proxyquire from 'proxyquire';
 import * as sinon from 'sinon';
 import {mkdirSync, writeFileSync} from 'fs';
 import * as fsp from 'fs/promises';
@@ -123,7 +123,7 @@ describe('grpc', () => {
     constructor(
       public address: {},
       public creds: {},
-      public options: {[index: string]: string | number | Function}
+      public options: {[index: string]: string | number | Function},
     ) {}
   }
 
@@ -184,22 +184,26 @@ describe('grpc', () => {
         port: 443,
         universeDomain: 'example.com',
       };
-      assert.rejects(
-        // @ts-ignore
-        grpcClient.createStub(DummyStub, opts),
-        /configured universe domain/
-      );
+      assert
+        .rejects(
+          // @ts-ignore
+          grpcClient.createStub(DummyStub, opts),
+          /configured universe domain/,
+        )
+        .catch(console.error);
     });
 
     it('validates universe domain if unset', async () => {
       const opts = {servicePath: 'foo.example.com', port: 443};
       stubAuth.getUniverseDomain.reset();
       stubAuth.getUniverseDomain.resolves('example.com');
-      assert.rejects(
-        // @ts-ignore
-        grpcClient.createStub(DummyStub, opts),
-        /configured universe domain/
-      );
+      assert
+        .rejects(
+          // @ts-ignore
+          grpcClient.createStub(DummyStub, opts),
+          /configured universe domain/,
+        )
+        .catch(console.error);
     });
 
     it('supports optional parameters', () => {
@@ -236,15 +240,15 @@ describe('grpc', () => {
         const dummyStub = stub as unknown as DummyStub;
         assert.strictEqual(
           dummyStub.options['grpc.max_send_message_length'],
-          10 * 1024 * 1024
+          10 * 1024 * 1024,
         );
         assert.strictEqual(
           (dummyStub.options['callInvocationTransformer'] as Function)(),
-          42
+          42,
         );
         assert.strictEqual(
           dummyStub.options['grpc-node.max_session_memory'],
-          10
+          10,
         );
         ['servicePath', 'port', 'other_dummy_options'].forEach(k => {
           assert.strictEqual(stub.options.hasOwnProperty(k), false);
@@ -290,7 +294,7 @@ describe('grpc', () => {
         const dummyStub = stub as unknown as DummyStub;
         assert.strictEqual(
           dummyStub.options['grpc.max_receive_message_length'],
-          10 * 1024 * 1024
+          10 * 1024 * 1024,
         );
       });
     });
@@ -323,14 +327,14 @@ describe('grpc', () => {
       'example',
       'library',
       'v1',
-      'library.proto'
+      'library.proto',
     );
     const TEST_FILE_NO_DEPS = path.join(
       'google',
       'example',
       'library',
       'v1',
-      'test.proto'
+      'test.proto',
     );
     const TEST_PATH = path.resolve(__dirname, '..', '..', 'test', 'fixtures');
     const TEST_JSON = path.resolve(
@@ -339,7 +343,7 @@ describe('grpc', () => {
       '..',
       'test',
       'fixtures',
-      'library.json'
+      'library.json',
     );
 
     it('should load the test file', () => {
@@ -349,7 +353,7 @@ describe('grpc', () => {
       const protos = grpcClient.loadProto(TEST_PATH, TEST_FILE) as any;
       assert.strictEqual(
         typeof protos.google.example.library.v1.LibraryService,
-        'function'
+        'function',
       );
     });
 
@@ -360,7 +364,7 @@ describe('grpc', () => {
       const protos = grpcClient.loadProtoJSON(require(TEST_JSON)) as any;
       assert.strictEqual(
         typeof protos.google.example.library.v1.LibraryService,
-        'function'
+        'function',
       );
     });
 
@@ -368,7 +372,7 @@ describe('grpc', () => {
       // no-any disabled because if the accessed fields are non-existent, this
       // test will fail anyway.
       const protos = grpcClient.loadProto(
-        path.join(TEST_PATH, TEST_FILE_NO_DEPS)
+        path.join(TEST_PATH, TEST_FILE_NO_DEPS),
         // eslint-disable-next-line @typescript-eslint/no-explicit-any
       ) as any;
       assert(protos.test.TestMessage);
@@ -400,7 +404,7 @@ describe('grpc', () => {
       ]) as any;
       assert.strictEqual(
         typeof protos.google.example.library.v1.LibraryService,
-        'function'
+        'function',
       );
       assert.strictEqual(typeof protos.google.iam.v1.IAMPolicy, 'function');
     });
@@ -409,7 +413,7 @@ describe('grpc', () => {
       const nonExistentDir = path.join(__dirname, 'nonexistent', 'dir');
       const nonExistentFile = 'nonexistent.proto';
       assert.throws(
-        grpcClient.loadProto.bind(null, nonExistentDir, nonExistentFile)
+        grpcClient.loadProto.bind(null, nonExistentDir, nonExistentFile),
       );
     });
 
@@ -436,12 +440,12 @@ describe('grpc', () => {
       const proto1 = grpcClient.loadProto(
         TEST_PATH,
         TEST_FILE,
-        /*ignoreCache:*/ true
+        /*ignoreCache:*/ true,
       );
       const proto2 = grpcClient.loadProto(
         TEST_PATH,
         TEST_FILE,
-        /*ignoreCache:*/ true
+        /*ignoreCache:*/ true,
       );
       assert.notStrictEqual(proto1, proto2);
     });
@@ -449,11 +453,11 @@ describe('grpc', () => {
     it('should ignore cache if asked for JSON protos', () => {
       const proto1 = grpcClient.loadProtoJSON(
         require(TEST_JSON),
-        /*ignoreCache:*/ true
+        /*ignoreCache:*/ true,
       );
       const proto2 = grpcClient.loadProtoJSON(
         require(TEST_JSON),
-        /*ignoreCache:*/ true
+        /*ignoreCache:*/ true,
       );
       assert.notStrictEqual(proto1, proto2);
     });
@@ -473,18 +477,18 @@ describe('grpc', () => {
       'google',
       'example',
       'library',
-      'v1'
+      'v1',
     );
     const TEST_FILE = path.join(FIXTURES_DIR, 'library.proto');
     const NON_EXISTENT_FILE = path.join(
       __dirname,
       'does',
       'not',
-      'exist.proto'
+      'exist.proto',
     );
     const MISSING_INCLUDE_FILE = path.join(
       FIXTURES_DIR,
-      'missing_include.proto'
+      'missing_include.proto',
     );
 
     describe('use with protobufjs load', () => {
@@ -495,7 +499,7 @@ describe('grpc', () => {
           },
           () => {
             done();
-          }
+          },
         );
       });
 
@@ -506,7 +510,7 @@ describe('grpc', () => {
             assert(root instanceof protobuf.Root);
             assert(
               root.lookup('google.example.library.v1.LibraryService') instanceof
-                protobuf.Service
+                protobuf.Service,
             );
             assert(root.lookup('test.TestMessage') instanceof protobuf.Type);
             done();
@@ -549,7 +553,7 @@ describe('grpc', () => {
         assert(root instanceof protobuf.Root);
         assert(
           root.lookup('google.example.library.v1.LibraryService') instanceof
-            protobuf.Service
+            protobuf.Service,
         );
         assert(root.lookup('test.TestMessage') instanceof protobuf.Type);
       });
@@ -559,8 +563,8 @@ describe('grpc', () => {
           protobuf.loadSync.bind(
             null,
             NON_EXISTENT_FILE,
-            new GoogleProtoFilesRoot()
-          )
+            new GoogleProtoFilesRoot(),
+          ),
         );
       });
 
@@ -569,8 +573,8 @@ describe('grpc', () => {
           protobuf.loadSync.bind(
             null,
             MISSING_INCLUDE_FILE,
-            new GoogleProtoFilesRoot()
-          )
+            new GoogleProtoFilesRoot(),
+          ),
         );
       });
     });
@@ -601,7 +605,7 @@ describe('grpc', () => {
         }).GoogleProtoFilesRoot._findIncludePath;
         assert.strictEqual(
           findIncludePath(originPath, includePath),
-          correctPath
+          correctPath,
         );
       });
     });
@@ -630,7 +634,7 @@ describe('grpc', () => {
       const servicePath = client._mtlsServicePath(
         'https://foo.googleapis.com',
         false,
-        true
+        true,
       );
       assert.strictEqual(servicePath, expected);
     });
@@ -641,7 +645,7 @@ describe('grpc', () => {
       const servicePath = client._mtlsServicePath(
         'https://foo.googleapis.com',
         false,
-        false
+        false,
       );
       assert.strictEqual(servicePath, expected);
     });
@@ -676,11 +680,17 @@ dvorak
       mkdirSync(tmpdir, {recursive: true});
       const metadataFile = path.join(tmpdir, 'context_aware_metadata.json');
       writeFileSync(metadataFile, JSON.stringify(metadataFileContents), 'utf8');
-      sandbox.stub(os, 'homedir').returns(tmpFolder);
       // Create a client and test the certificate detection flow:
       process.env.GOOGLE_API_USE_CLIENT_CERTIFICATE = 'true';
-      const client = gaxGrpc();
-      const [cert, key] = await client._detectClientCertificate();
+      const {GrpcClient} = await proxyquire('../../src/grpc.js', {
+        os: {
+          homedir: () => {
+            return tmpFolder;
+          },
+        },
+      });
+      const clientMock = new GrpcClient();
+      const [cert, key] = await clientMock._detectClientCertificate();
       assert.ok(cert.includes('qwerty'));
       assert.ok(key.includes('dvorak'));
       await fsp.rm(tmpFolder, {recursive: true, force: true}); // Cleanup.
@@ -693,15 +703,24 @@ dvorak
       mkdirSync(tmpdir, {recursive: true});
       const metadataFile = path.join(tmpdir, 'context_aware_metadata.json');
       writeFileSync(metadataFile, JSON.stringify(metadataFileContents), 'utf8');
-      sandbox.stub(os, 'homedir').returns(tmpFolder);
+
+      process.env.GOOGLE_API_USE_CLIENT_CERTIFICATE = 'true';
+      const {GrpcClient} = await proxyquire('../../src/grpc.js', {
+        os: {
+          homedir: () => {
+            return tmpFolder;
+          },
+        },
+      });
       // Create a client and test the certificate detection flow:
       process.env.GOOGLE_API_USE_CLIENT_CERTIFICATE = 'true';
-      const client = gaxGrpc();
-      assert.rejects(
-        // @ts-ignore
-        client.createStub(DummyStub, {universeDomain: 'example.com'}),
-        /configured universe domain/
-      );
+      const clientMock = new GrpcClient();
+      assert
+        .rejects(
+          clientMock.createStub(DummyStub, {universeDomain: 'example.com'}),
+          /configured universe domain/,
+        )
+        .catch(console.error);
       await fsp.rm(tmpFolder, {recursive: true, force: true}); // Cleanup.
     });
   });
diff --git a/gax/test/unit/iamService.ts b/gax/test/unit/iamService.ts
index bfeec0abc..56c88ddb4 100644
--- a/gax/test/unit/iamService.ts
+++ b/gax/test/unit/iamService.ts
@@ -15,8 +15,9 @@
 // ** This file is automatically generated by gapic-generator-typescript. **
 // ** https://github.com/googleapis/gapic-generator-typescript **
 // ** All changes to this file may be overwritten. **
+
 import * as protos from '../../protos/iam_service';
-import * as assert from 'assert';
+import assert from 'assert';
 import * as sinon from 'sinon';
 import {SinonStub} from 'sinon';
 import {describe, it} from 'mocha';
@@ -29,7 +30,7 @@ function generateSampleMessage<T extends object>(instance: T) {
     instance.constructor as typeof protobuf.Message
   ).toObject(instance as protobuf.Message<T>, {defaults: true});
   return (instance.constructor as typeof protobuf.Message).fromObject(
-    filledObject
+    filledObject,
   ) as T;
 }
 
@@ -41,7 +42,7 @@ function stubSimpleCall<ResponseType>(response?: ResponseType, error?: Error) {
 
 function stubSimpleCallWithCallback<ResponseType>(
   response?: ResponseType,
-  error?: Error
+  error?: Error,
 ) {
   return error
     ? sinon.stub().callsArgWith(2, error)
@@ -56,9 +57,9 @@ describe('IAM service', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.iam.v1.GetIamPolicyRequest()
+        new protos.google.iam.v1.GetIamPolicyRequest(),
       );
       request.resource = '';
       const expectedHeaderRequestParams = 'resource=';
@@ -70,7 +71,7 @@ describe('IAM service', () => {
         },
       };
       const expectedResponse = generateSampleMessage(
-        new protos.google.iam.v1.Policy()
+        new protos.google.iam.v1.Policy(),
       );
       client.innerApiCalls.getIamPolicy = stubSimpleCall(expectedResponse);
       const response = await client.getIamPolicy(request, expectedOptions);
@@ -78,7 +79,7 @@ describe('IAM service', () => {
       assert(
         (client.innerApiCalls.getIamPolicy as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
     it('invokes getIamPolicy without error using callback', async () => {
@@ -87,9 +88,9 @@ describe('IAM service', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.iam.v1.GetIamPolicyRequest()
+        new protos.google.iam.v1.GetIamPolicyRequest(),
       );
       request.resource = '';
       const expectedHeaderRequestParams = 'resource=';
@@ -101,29 +102,34 @@ describe('IAM service', () => {
         },
       };
       const expectedResponse = generateSampleMessage(
-        new protos.google.iam.v1.Policy()
+        new protos.google.iam.v1.Policy(),
       );
       client.innerApiCalls.getIamPolicy =
         stubSimpleCallWithCallback(expectedResponse);
       const promise = new Promise((resolve, reject) => {
-        client.getIamPolicy(
-          request,
-          expectedOptions,
-          (err?: Error | null, result?: protos.google.iam.v1.Policy | null) => {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(result);
-            }
-          }
-        );
+        client
+          .getIamPolicy(
+            request,
+            expectedOptions,
+            (
+              err?: Error | null,
+              result?: protos.google.iam.v1.Policy | null,
+            ) => {
+              if (err) {
+                reject(err);
+              } else {
+                resolve(result);
+              }
+            },
+          )
+          .catch(console.error);
       });
       const response = await promise;
       assert.deepStrictEqual(response, expectedResponse);
       assert(
         (client.innerApiCalls.getIamPolicy as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions /* callback function above */)
+          .calledWith(request, expectedOptions /* callback function above */),
       );
     });
     it('invokes getIamPolicy with error', async () => {
@@ -132,9 +138,9 @@ describe('IAM service', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.iam.v1.GetIamPolicyRequest()
+        new protos.google.iam.v1.GetIamPolicyRequest(),
       );
       request.resource = '';
       const expectedHeaderRequestParams = 'resource=';
@@ -148,7 +154,7 @@ describe('IAM service', () => {
       const expectedError = new Error('expected');
       client.innerApiCalls.getIamPolicy = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(async () => {
         await client.getIamPolicy(request, expectedOptions);
@@ -156,7 +162,7 @@ describe('IAM service', () => {
       assert(
         (client.innerApiCalls.getIamPolicy as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
   });
@@ -167,9 +173,9 @@ describe('IAM service', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.iam.v1.SetIamPolicyRequest()
+        new protos.google.iam.v1.SetIamPolicyRequest(),
       );
       request.resource = '';
       const expectedHeaderRequestParams = 'resource=';
@@ -181,7 +187,7 @@ describe('IAM service', () => {
         },
       };
       const expectedResponse = generateSampleMessage(
-        new protos.google.iam.v1.Policy()
+        new protos.google.iam.v1.Policy(),
       );
       client.innerApiCalls.setIamPolicy = stubSimpleCall(expectedResponse);
       const response = await client.setIamPolicy(request, expectedOptions);
@@ -189,7 +195,7 @@ describe('IAM service', () => {
       assert(
         (client.innerApiCalls.setIamPolicy as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
     it('invokes setIamPolicy without error using callback', async () => {
@@ -198,9 +204,9 @@ describe('IAM service', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.iam.v1.SetIamPolicyRequest()
+        new protos.google.iam.v1.SetIamPolicyRequest(),
       );
       request.resource = '';
       const expectedHeaderRequestParams = 'resource=';
@@ -212,29 +218,34 @@ describe('IAM service', () => {
         },
       };
       const expectedResponse = generateSampleMessage(
-        new protos.google.iam.v1.Policy()
+        new protos.google.iam.v1.Policy(),
       );
       client.innerApiCalls.setIamPolicy =
         stubSimpleCallWithCallback(expectedResponse);
       const promise = new Promise((resolve, reject) => {
-        client.setIamPolicy(
-          request,
-          expectedOptions,
-          (err?: Error | null, result?: protos.google.iam.v1.Policy | null) => {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(result);
-            }
-          }
-        );
+        client
+          .setIamPolicy(
+            request,
+            expectedOptions,
+            (
+              err?: Error | null,
+              result?: protos.google.iam.v1.Policy | null,
+            ) => {
+              if (err) {
+                reject(err);
+              } else {
+                resolve(result);
+              }
+            },
+          )
+          .catch(console.error);
       });
       const response = await promise;
       assert.deepStrictEqual(response, expectedResponse);
       assert(
         (client.innerApiCalls.setIamPolicy as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions /* callback function above */)
+          .calledWith(request, expectedOptions /* callback function above */),
       );
     });
     it('invokes setIamPolicy with error', async () => {
@@ -243,9 +254,9 @@ describe('IAM service', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.iam.v1.SetIamPolicyRequest()
+        new protos.google.iam.v1.SetIamPolicyRequest(),
       );
       request.resource = '';
       const expectedHeaderRequestParams = 'resource=';
@@ -259,7 +270,7 @@ describe('IAM service', () => {
       const expectedError = new Error('expected');
       client.innerApiCalls.setIamPolicy = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(async () => {
         await client.setIamPolicy(request, expectedOptions);
@@ -267,7 +278,7 @@ describe('IAM service', () => {
       assert(
         (client.innerApiCalls.setIamPolicy as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
   });
@@ -278,9 +289,9 @@ describe('IAM service', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.iam.v1.TestIamPermissionsRequest()
+        new protos.google.iam.v1.TestIamPermissionsRequest(),
       );
       request.resource = '';
       const expectedHeaderRequestParams = 'resource=';
@@ -292,19 +303,19 @@ describe('IAM service', () => {
         },
       };
       const expectedResponse = generateSampleMessage(
-        new protos.google.iam.v1.TestIamPermissionsResponse()
+        new protos.google.iam.v1.TestIamPermissionsResponse(),
       );
       client.innerApiCalls.testIamPermissions =
         stubSimpleCall(expectedResponse);
       const response = await client.testIamPermissions(
         request,
-        expectedOptions
+        expectedOptions,
       );
       assert.deepStrictEqual(response, [expectedResponse]);
       assert(
         (client.innerApiCalls.testIamPermissions as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
     it('invokes testIamPermissions without error using callback', async () => {
@@ -313,9 +324,9 @@ describe('IAM service', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.iam.v1.TestIamPermissionsRequest()
+        new protos.google.iam.v1.TestIamPermissionsRequest(),
       );
       request.resource = '';
       const expectedHeaderRequestParams = 'resource=';
@@ -327,32 +338,34 @@ describe('IAM service', () => {
         },
       };
       const expectedResponse = generateSampleMessage(
-        new protos.google.iam.v1.TestIamPermissionsResponse()
+        new protos.google.iam.v1.TestIamPermissionsResponse(),
       );
       client.innerApiCalls.testIamPermissions =
         stubSimpleCallWithCallback(expectedResponse);
       const promise = new Promise((resolve, reject) => {
-        client.testIamPermissions(
-          request,
-          expectedOptions,
-          (
-            err?: Error | null,
-            result?: protos.google.iam.v1.TestIamPermissionsResponse | null
-          ) => {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(result);
-            }
-          }
-        );
+        client
+          .testIamPermissions(
+            request,
+            expectedOptions,
+            (
+              err?: Error | null,
+              result?: protos.google.iam.v1.TestIamPermissionsResponse | null,
+            ) => {
+              if (err) {
+                reject(err);
+              } else {
+                resolve(result);
+              }
+            },
+          )
+          .catch(console.error);
       });
       const response = await promise;
       assert.deepStrictEqual(response, expectedResponse);
       assert(
         (client.innerApiCalls.testIamPermissions as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions /* callback function above */)
+          .calledWith(request, expectedOptions /* callback function above */),
       );
     });
     it('invokes testIamPermissions with error', async () => {
@@ -361,9 +374,9 @@ describe('IAM service', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.iam.v1.TestIamPermissionsRequest()
+        new protos.google.iam.v1.TestIamPermissionsRequest(),
       );
       request.resource = '';
       const expectedHeaderRequestParams = 'resource=';
@@ -377,7 +390,7 @@ describe('IAM service', () => {
       const expectedError = new Error('expected');
       client.innerApiCalls.testIamPermissions = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(async () => {
         await client.testIamPermissions(request, expectedOptions);
@@ -385,7 +398,7 @@ describe('IAM service', () => {
       assert(
         (client.innerApiCalls.testIamPermissions as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
   });
diff --git a/gax/test/unit/locationService.ts b/gax/test/unit/locationService.ts
index 8d957cb41..cb2119cb5 100644
--- a/gax/test/unit/locationService.ts
+++ b/gax/test/unit/locationService.ts
@@ -13,7 +13,7 @@
 // limitations under the License.
 
 import * as protos from '../../protos/locations';
-import * as assert from 'assert';
+import assert from 'assert';
 import * as sinon from 'sinon';
 import {SinonStub} from 'sinon';
 import {describe, it} from 'mocha';
@@ -27,7 +27,7 @@ function generateSampleMessage<T extends object>(instance: T) {
     instance.constructor as typeof protobuf.Message
   ).toObject(instance as protobuf.Message<T>, {defaults: true});
   return (instance.constructor as typeof protobuf.Message).fromObject(
-    filledObject
+    filledObject,
   ) as T;
 }
 
@@ -39,7 +39,7 @@ function stubSimpleCall<ResponseType>(response?: ResponseType, error?: Error) {
 
 function stubSimpleCallWithCallback<ResponseType>(
   response?: ResponseType,
-  error?: Error
+  error?: Error,
 ) {
   return error
     ? sinon.stub().callsArgWith(2, error)
@@ -48,7 +48,7 @@ function stubSimpleCallWithCallback<ResponseType>(
 
 function stubAsyncIterationCall<ResponseType>(
   responses?: ResponseType[],
-  error?: Error
+  error?: Error,
 ) {
   let counter = 0;
   const asyncIterable = {
@@ -77,9 +77,9 @@ describe('LocationsClient', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.cloud.location.GetLocationRequest()
+        new protos.google.cloud.location.GetLocationRequest(),
       );
       request.name = '';
       const expectedHeaderRequestParams = 'name=';
@@ -91,7 +91,7 @@ describe('LocationsClient', () => {
         },
       };
       const expectedResponse = generateSampleMessage(
-        new protos.google.cloud.location.Location()
+        new protos.google.cloud.location.Location(),
       );
       client.innerApiCalls.getLocation = stubSimpleCall(expectedResponse);
       const response = await client.getLocation(request, expectedOptions);
@@ -99,7 +99,7 @@ describe('LocationsClient', () => {
       assert(
         (client.innerApiCalls.getLocation as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
 
@@ -109,9 +109,9 @@ describe('LocationsClient', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.cloud.location.GetLocationRequest()
+        new protos.google.cloud.location.GetLocationRequest(),
       );
       request.name = '';
       const expectedHeaderRequestParams = 'name=';
@@ -123,31 +123,33 @@ describe('LocationsClient', () => {
         },
       };
       const expectedResponse = generateSampleMessage(
-        new protos.google.cloud.location.Location()
+        new protos.google.cloud.location.Location(),
       );
       client.innerApiCalls.getLocation =
         stubSimpleCallWithCallback(expectedResponse);
       const promise = new Promise((resolve, reject) => {
-        client.getLocation(
-          request,
-          (
-            err?: Error | null,
-            result?: protos.google.cloud.location.ILocation | null
-          ) => {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(result);
-            }
-          }
-        );
+        client
+          .getLocation(
+            request,
+            (
+              err?: Error | null,
+              result?: protos.google.cloud.location.ILocation | null,
+            ) => {
+              if (err) {
+                reject(err);
+              } else {
+                resolve(result);
+              }
+            },
+          )
+          .catch(console.error);
       });
       const response = await promise;
       assert.deepStrictEqual(response, expectedResponse);
       assert(
         (client.innerApiCalls.getLocation as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions /*, callback defined above */)
+          .calledWith(request, expectedOptions /*, callback defined above */),
       );
     });
 
@@ -156,9 +158,9 @@ describe('LocationsClient', () => {
       const client = new LocationsClient(grpcClient, {
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.cloud.location.GetLocationRequest()
+        new protos.google.cloud.location.GetLocationRequest(),
       );
       request.name = '';
       const expectedHeaderRequestParams = 'name=';
@@ -172,16 +174,16 @@ describe('LocationsClient', () => {
       const expectedError = new Error('expected');
       client.innerApiCalls.getLocation = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(
         client.getLocation(request, expectedOptions),
-        expectedError
+        expectedError,
       );
       assert(
         (client.innerApiCalls.getLocation as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
   });
@@ -193,9 +195,9 @@ describe('LocationsClient', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.cloud.location.ListLocationsRequest()
+        new protos.google.cloud.location.ListLocationsRequest(),
       );
       request.name = '';
       const expectedHeaderRequestParams = 'name=';
@@ -217,7 +219,7 @@ describe('LocationsClient', () => {
       assert(
         (client.innerApiCalls.listLocations as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
 
@@ -227,9 +229,9 @@ describe('LocationsClient', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.cloud.location.ListLocationsRequest()
+        new protos.google.cloud.location.ListLocationsRequest(),
       );
       request.name = '';
       const expectedHeaderRequestParams = 'name=';
@@ -252,14 +254,14 @@ describe('LocationsClient', () => {
           request,
           (
             err?: Error | null,
-            result?: protos.google.cloud.location.ILocation[] | null
+            result?: protos.google.cloud.location.ILocation[] | null,
           ) => {
             if (err) {
               reject(err);
             } else {
               resolve(result);
             }
-          }
+          },
         );
       });
       const response = await promise;
@@ -267,7 +269,7 @@ describe('LocationsClient', () => {
       assert(
         (client.innerApiCalls.listLocations as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions /*, callback defined above */)
+          .calledWith(request, expectedOptions /*, callback defined above */),
       );
     });
 
@@ -277,9 +279,9 @@ describe('LocationsClient', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.cloud.location.ListLocationsRequest()
+        new protos.google.cloud.location.ListLocationsRequest(),
       );
       request.name = '';
       const expectedHeaderRequestParams = 'name=';
@@ -293,16 +295,16 @@ describe('LocationsClient', () => {
       const expectedError = new Error('expected');
       client.innerApiCalls.listLocations = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(
         client.listLocations(request, expectedOptions),
-        expectedError
+        expectedError,
       );
       assert(
         (client.innerApiCalls.listLocations as SinonStub)
           .getCall(0)
-          .calledWith(request, expectedOptions, undefined)
+          .calledWith(request, expectedOptions, undefined),
       );
     });
 
@@ -312,9 +314,9 @@ describe('LocationsClient', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.cloud.location.ListLocationsRequest()
+        new protos.google.cloud.location.ListLocationsRequest(),
       );
       request.name = '';
       const expectedHeaderRequestParams = 'name=';
@@ -335,13 +337,13 @@ describe('LocationsClient', () => {
         (
           client.descriptors.page.listLocations.asyncIterate as SinonStub
         ).getCall(0).args[1],
-        request
+        request,
       );
       assert.strictEqual(
         (
           client.descriptors.page.listLocations.asyncIterate as SinonStub
         ).getCall(0).args[2].otherArgs.headers['x-goog-request-params'],
-        expectedHeaderRequestParams
+        expectedHeaderRequestParams,
       );
     });
 
@@ -351,9 +353,9 @@ describe('LocationsClient', () => {
         credentials: {client_email: 'bogus', private_key: 'bogus'},
         projectId: 'bogus',
       });
-      client.initialize();
+      client.initialize().catch(console.error);
       const request = generateSampleMessage(
-        new protos.google.cloud.location.ListLocationsRequest()
+        new protos.google.cloud.location.ListLocationsRequest(),
       );
       request.name = '';
       const expectedHeaderRequestParams = 'name=';
@@ -371,13 +373,13 @@ describe('LocationsClient', () => {
         (
           client.descriptors.page.listLocations.asyncIterate as SinonStub
         ).getCall(0).args[1],
-        request
+        request,
       );
       assert.strictEqual(
         (
           client.descriptors.page.listLocations.asyncIterate as SinonStub
         ).getCall(0).args[2].otherArgs.headers['x-goog-request-params'],
-        expectedHeaderRequestParams
+        expectedHeaderRequestParams,
       );
     });
   });
diff --git a/gax/test/unit/longrunning.ts b/gax/test/unit/longrunning.ts
index 0ec804a3c..ce48e7854 100644
--- a/gax/test/unit/longrunning.ts
+++ b/gax/test/unit/longrunning.ts
@@ -16,7 +16,7 @@
 
 /* eslint-disable no-prototype-builtins */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {status} from '@grpc/grpc-js';
 import * as sinon from 'sinon';
 import {describe, it} from 'mocha';
@@ -85,7 +85,7 @@ function createApiCall(func: Function, client?: OperationsClient) {
   const descriptor = new LongrunningDescriptor(
     client!,
     mockDecoder as unknown as AnyDecoder,
-    mockDecoder as unknown as AnyDecoder
+    mockDecoder as unknown as AnyDecoder,
   );
   return utils.createApiCall(func, {descriptor}) as GaxCallPromise;
 }
@@ -140,7 +140,7 @@ describe('longrunning', () => {
         argument: {},
         metadata: {},
         options: {},
-        callback: Function
+        callback: Function,
       ) => {
         callback(null, PENDING_OP);
       };
@@ -157,19 +157,19 @@ describe('longrunning', () => {
           assert(operation.hasOwnProperty('backoffSettings'));
           assert.strictEqual(
             operation.backoffSettings.initialRetryDelayMillis,
-            defaultInitialRetryDelayMillis
+            defaultInitialRetryDelayMillis,
           );
           assert.strictEqual(
             operation.backoffSettings.retryDelayMultiplier,
-            defaultRetryDelayMultiplier
+            defaultRetryDelayMultiplier,
           );
           assert.strictEqual(
             operation.backoffSettings.maxRetryDelayMillis,
-            defaultMaxRetryDelayMillis
+            defaultMaxRetryDelayMillis,
           );
           assert.strictEqual(
             operation.backoffSettings.totalTimeoutMillis,
-            defaultTotalTimeoutMillis
+            defaultTotalTimeoutMillis,
           );
           assert(operation.hasOwnProperty('longrunningDescriptor'));
           assert.strictEqual(operation.name, OPERATION_NAME);
@@ -190,7 +190,7 @@ describe('longrunning', () => {
       const desc = new LongrunningDescriptor(
         client as OperationsClient,
         mockDecoder as unknown as AnyDecoder,
-        mockDecoder as unknown as AnyDecoder
+        mockDecoder as unknown as AnyDecoder,
       );
       const initialRetryDelayMillis = 1;
       const retryDelayMultiplier = 2;
@@ -204,30 +204,30 @@ describe('longrunning', () => {
         unusedRpcValue,
         unusedRpcValue,
         unusedRpcValue,
-        totalTimeoutMillis
+        totalTimeoutMillis,
       );
       const operation = longrunning.operation(
         SUCCESSFUL_OP as {} as operationProtos.google.longrunning.Operation,
         desc,
-        backoff
+        backoff,
       );
       assert(operation instanceof Object);
       assert(operation.hasOwnProperty('backoffSettings'));
       assert.strictEqual(
         operation.backoffSettings.initialRetryDelayMillis,
-        initialRetryDelayMillis
+        initialRetryDelayMillis,
       );
       assert.strictEqual(
         operation.backoffSettings.retryDelayMultiplier,
-        retryDelayMultiplier
+        retryDelayMultiplier,
       );
       assert.strictEqual(
         operation.backoffSettings.maxRetryDelayMillis,
-        maxRetryDelayMillis
+        maxRetryDelayMillis,
       );
       assert.strictEqual(
         operation.backoffSettings.totalTimeoutMillis,
-        totalTimeoutMillis
+        totalTimeoutMillis,
       );
       assert(operation.hasOwnProperty('longrunningDescriptor'));
       assert.strictEqual(operation.name, OPERATION_NAME);
@@ -247,7 +247,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, SUCCESSFUL_OP);
         };
@@ -275,7 +275,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -305,7 +305,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -325,7 +325,7 @@ describe('longrunning', () => {
                 assert.strictEqual(client.getOperation.callCount, 1);
                 done();
               }),
-              undefined
+              undefined,
             );
           })
           .catch(error => {
@@ -338,7 +338,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -370,7 +370,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, ERROR_OP);
         };
@@ -397,7 +397,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -428,7 +428,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, SUCCESSFUL_OP);
         };
@@ -449,7 +449,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -481,7 +481,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -509,7 +509,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -522,11 +522,14 @@ describe('longrunning', () => {
           .then(responses => {
             const operation = responses[0] as longrunning.Operation;
             const p = operation.promise();
-            operation.cancel().then(() => {
-              assert.strictEqual(client.cancelOperation.called, true);
-              assert.strictEqual(client.cancelGetOperationSpy.called, true);
-              done();
-            });
+            operation
+              .cancel()
+              .then(() => {
+                assert.strictEqual(client.cancelOperation.called, true);
+                assert.strictEqual(client.cancelGetOperationSpy.called, true);
+                done();
+              })
+              .catch(console.error);
             return p;
           })
           .then(() => {
@@ -544,7 +547,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -577,7 +580,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -610,7 +613,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -646,7 +649,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -699,7 +702,7 @@ describe('longrunning', () => {
           argument: {},
           metadata: {},
           options: {},
-          callback: Function
+          callback: Function,
         ) => {
           callback(null, PENDING_OP);
         };
@@ -713,7 +716,7 @@ describe('longrunning', () => {
           {},
           {
             longrunning: gax.createBackoffSettings(1, 1, 1, 0, 0, 0, 1),
-          }
+          },
         )
           .then(responses => {
             const operation = responses[0] as longrunning.Operation;
@@ -725,7 +728,7 @@ describe('longrunning', () => {
               assert.strictEqual(err!.code, status.DEADLINE_EXCEEDED);
               assert.strictEqual(
                 err!.message,
-                'Total timeout exceeded before ' + 'any response was received'
+                'Total timeout exceeded before ' + 'any response was received',
               );
               done();
             });
diff --git a/gax/test/unit/operationClient.ts b/gax/test/unit/operationClient.ts
index 0d910b8cb..f3d7a6f7e 100644
--- a/gax/test/unit/operationClient.ts
+++ b/gax/test/unit/operationClient.ts
@@ -15,8 +15,9 @@
 // ** This file is automatically generated by gapic-generator-typescript. **
 // ** https://github.com/googleapis/gapic-generator-typescript **
 // ** All changes to this file may be overwritten. **
+
 import * as protos from '../../protos/operations';
-import * as assert from 'assert';
+import assert from 'assert';
 import * as sinon from 'sinon';
 import {SinonStub} from 'sinon';
 import {describe, it} from 'mocha';
@@ -31,7 +32,7 @@ function generateSampleMessage<T extends object>(instance: T) {
     instance.constructor as typeof protobuf.Message
   ).toObject(instance as protobuf.Message<T>, {defaults: true});
   return (instance.constructor as typeof protobuf.Message).fromObject(
-    filledObject
+    filledObject,
   ) as T;
 }
 
@@ -43,7 +44,7 @@ function stubSimpleCall<ResponseType>(response?: ResponseType, error?: Error) {
 
 function stubSimpleCallWithCallback<ResponseType>(
   response?: ResponseType,
-  error?: Error
+  error?: Error,
 ) {
   return error
     ? sinon.stub().callsArgWith(2, error)
@@ -51,7 +52,7 @@ function stubSimpleCallWithCallback<ResponseType>(
 }
 function stubPageStreamingCall<ResponseType>(
   responses?: ResponseType[],
-  error?: Error
+  error?: Error,
 ) {
   const pagingStub = sinon.stub();
   if (responses) {
@@ -89,7 +90,7 @@ function stubPageStreamingCall<ResponseType>(
 
 function stubAsyncIterationCall<ResponseType>(
   responses?: ResponseType[],
-  error?: Error
+  error?: Error,
 ) {
   let counter = 0;
   const asyncIterable = {
@@ -119,14 +120,14 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.GetOperationRequest()
+        new protos.google.longrunning.GetOperationRequest(),
       );
       const expectedResponse = generateSampleMessage(
-        new protos.google.longrunning.Operation()
+        new protos.google.longrunning.Operation(),
       );
       client.innerApiCalls.getOperation = stubSimpleCall(expectedResponse);
       const response = await client.getOperation(request);
@@ -134,7 +135,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.getOperation as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
 
@@ -145,39 +146,41 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.GetOperationRequest()
+        new protos.google.longrunning.GetOperationRequest(),
       );
       const expectedResponse = generateSampleMessage(
-        new protos.google.longrunning.Operation()
+        new protos.google.longrunning.Operation(),
       );
       client.innerApiCalls.getOperation =
         stubSimpleCallWithCallback(expectedResponse);
       const promise = new Promise((resolve, reject) => {
-        client.getOperation(
-          request,
-          undefined,
-          (
-            err?: Error | null,
-            result?: protos.google.longrunning.Operation | null
-          ) => {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(result);
-            }
-          }
-        );
+        client
+          .getOperation(
+            request,
+            undefined,
+            (
+              err?: Error | null,
+              result?: protos.google.longrunning.Operation | null,
+            ) => {
+              if (err) {
+                reject(err);
+              } else {
+                resolve(result);
+              }
+            },
+          )
+          .catch(console.error);
       });
       const response = await promise;
       assert.deepStrictEqual(response, expectedResponse);
       assert(
         (client.innerApiCalls.getOperation as SinonStub)
           .getCall(0)
-          .calledWith(request /* callback function above */)
+          .calledWith(request /* callback function above */),
       );
     });
 
@@ -188,15 +191,15 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
       const request = generateSampleMessage(
-        new protos.google.longrunning.GetOperationRequest()
+        new protos.google.longrunning.GetOperationRequest(),
       );
       const expectedError = new Error('expected');
       client.innerApiCalls.getOperation = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(async () => {
         await client.getOperation(request);
@@ -204,7 +207,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.getOperation as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
   });
@@ -216,11 +219,11 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.GetOperationRequest()
+        new protos.google.longrunning.GetOperationRequest(),
       );
       const expectedResponse: ResultTuple = [
         new protos.google.longrunning.Operation(),
@@ -233,7 +236,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.getOperation as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
 
@@ -244,11 +247,11 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.GetOperationRequest()
+        new protos.google.longrunning.GetOperationRequest(),
       );
       const expectedResponse: ResultTuple = [
         new protos.google.longrunning.Operation(),
@@ -258,27 +261,29 @@ describe('operation client', () => {
       client.innerApiCalls.getOperation =
         stubSimpleCallWithCallback(expectedResponse);
       const promise = new Promise((resolve, reject) => {
-        client.getOperationInternal(
-          request,
-          undefined,
-          (
-            err?: Error | null,
-            result?: protos.google.longrunning.Operation | null
-          ) => {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(result);
-            }
-          }
-        );
+        client
+          .getOperationInternal(
+            request,
+            undefined,
+            (
+              err?: Error | null,
+              result?: protos.google.longrunning.Operation | null,
+            ) => {
+              if (err) {
+                reject(err);
+              } else {
+                resolve(result);
+              }
+            },
+          )
+          .catch(console.error);
       });
       const response = await promise;
       assert.deepStrictEqual(response, expectedResponse);
       assert(
         (client.innerApiCalls.getOperation as SinonStub)
           .getCall(0)
-          .calledWith(request /* callback function above */)
+          .calledWith(request /* callback function above */),
       );
     });
 
@@ -289,15 +294,15 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
       const request = generateSampleMessage(
-        new protos.google.longrunning.GetOperationRequest()
+        new protos.google.longrunning.GetOperationRequest(),
       );
       const expectedError = new Error('expected');
       client.innerApiCalls.getOperation = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(async () => {
         await client.getOperationInternal(request);
@@ -305,7 +310,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.getOperation as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
   });
@@ -317,14 +322,14 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.ListOperationsRequest()
+        new protos.google.longrunning.ListOperationsRequest(),
       );
       const expectedResponse = generateSampleMessage(
-        new protos.google.longrunning.ListOperationsResponse()
+        new protos.google.longrunning.ListOperationsResponse(),
       );
       client.innerApiCalls.listOperations = stubSimpleCall(expectedResponse);
       const response = await client.listOperations(request);
@@ -332,7 +337,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.listOperations as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
 
@@ -343,39 +348,41 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.ListOperationsRequest()
+        new protos.google.longrunning.ListOperationsRequest(),
       );
       const expectedResponse = generateSampleMessage(
-        new protos.google.longrunning.ListOperationsResponse()
+        new protos.google.longrunning.ListOperationsResponse(),
       );
       client.innerApiCalls.listOperations =
         stubSimpleCallWithCallback(expectedResponse);
       const promise = new Promise((resolve, reject) => {
-        client.listOperations(
-          request,
-          undefined,
-          (
-            err?: Error | null,
-            result?: protos.google.longrunning.ListOperationsResponse | null
-          ) => {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(result);
-            }
-          }
-        );
+        client
+          .listOperations(
+            request,
+            undefined,
+            (
+              err?: Error | null,
+              result?: protos.google.longrunning.ListOperationsResponse | null,
+            ) => {
+              if (err) {
+                reject(err);
+              } else {
+                resolve(result);
+              }
+            },
+          )
+          .catch(console.error);
       });
       const response = await promise;
       assert.deepStrictEqual(response, expectedResponse);
       assert(
         (client.innerApiCalls.listOperations as SinonStub)
           .getCall(0)
-          .calledWith(request /* callback function above */)
+          .calledWith(request /* callback function above */),
       );
     });
 
@@ -386,15 +393,15 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
       const request = generateSampleMessage(
-        new protos.google.longrunning.ListOperationsRequest()
+        new protos.google.longrunning.ListOperationsRequest(),
       );
       const expectedError = new Error('expected');
       client.innerApiCalls.listOperations = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(async () => {
         await client.listOperations(request);
@@ -402,7 +409,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.listOperations as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
 
@@ -413,11 +420,11 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.ListOperationsRequest()
+        new protos.google.longrunning.ListOperationsRequest(),
       );
       const expectedResponse = [
         generateSampleMessage(new protos.google.longrunning.Operation()),
@@ -444,7 +451,7 @@ describe('operation client', () => {
       assert(
         (client.descriptor.listOperations.createStream as SinonStub)
           .getCall(0)
-          .calledWith(client.innerApiCalls.listOperations, request)
+          .calledWith(client.innerApiCalls.listOperations, request),
       );
     });
 
@@ -455,16 +462,16 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.ListOperationsRequest()
+        new protos.google.longrunning.ListOperationsRequest(),
       );
       const expectedError = new Error('expected');
       client.descriptor.listOperations.createStream = stubPageStreamingCall(
         undefined,
-        expectedError
+        expectedError,
       );
       const stream = client.listOperationsStream(request);
       const promise = new Promise((resolve, reject) => {
@@ -485,7 +492,7 @@ describe('operation client', () => {
       assert(
         (client.descriptor.listOperations.createStream as SinonStub)
           .getCall(0)
-          .calledWith(client.innerApiCalls.listOperations, request)
+          .calledWith(client.innerApiCalls.listOperations, request),
       );
     });
 
@@ -496,21 +503,21 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.ListOperationsRequest()
+        new protos.google.longrunning.ListOperationsRequest(),
       );
       const expectedResponse = [
         generateSampleMessage(
-          new protos.google.longrunning.ListOperationsResponse()
+          new protos.google.longrunning.ListOperationsResponse(),
         ),
         generateSampleMessage(
-          new protos.google.longrunning.ListOperationsResponse()
+          new protos.google.longrunning.ListOperationsResponse(),
         ),
         generateSampleMessage(
-          new protos.google.longrunning.ListOperationsResponse()
+          new protos.google.longrunning.ListOperationsResponse(),
         ),
       ];
       client.descriptor.listOperations.asyncIterate =
@@ -524,7 +531,7 @@ describe('operation client', () => {
       assert.deepStrictEqual(
         (client.descriptor.listOperations.asyncIterate as SinonStub).getCall(0)
           .args[1],
-        request
+        request,
       );
     });
 
@@ -535,15 +542,15 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
       const request = generateSampleMessage(
-        new protos.google.longrunning.ListOperationsRequest()
+        new protos.google.longrunning.ListOperationsRequest(),
       );
       const expectedError = new Error('expected');
       client.descriptor.listOperations.asyncIterate = stubAsyncIterationCall(
         undefined,
-        expectedError
+        expectedError,
       );
       const iterable = client.listOperationsAsync(request);
       await assert.rejects(async () => {
@@ -555,7 +562,7 @@ describe('operation client', () => {
       });
       assert.deepStrictEqual(
         (client.descriptor.listOperations.asyncIterate as SinonStub).args[0][1],
-        request
+        request,
       );
     });
   });
@@ -567,14 +574,14 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.CancelOperationRequest()
+        new protos.google.longrunning.CancelOperationRequest(),
       );
       const expectedResponse = generateSampleMessage(
-        new protos.google.protobuf.Empty()
+        new protos.google.protobuf.Empty(),
       );
       client.innerApiCalls.cancelOperation = stubSimpleCall(expectedResponse);
       const response = await client.cancelOperation(request);
@@ -582,7 +589,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.cancelOperation as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
 
@@ -593,39 +600,41 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.CancelOperationRequest()
+        new protos.google.longrunning.CancelOperationRequest(),
       );
       const expectedResponse = generateSampleMessage(
-        new protos.google.protobuf.Empty()
+        new protos.google.protobuf.Empty(),
       );
       client.innerApiCalls.cancelOperation =
         stubSimpleCallWithCallback(expectedResponse);
       const promise = new Promise((resolve, reject) => {
-        client.cancelOperation(
-          request,
-          undefined,
-          (
-            err?: Error | null,
-            result?: protos.google.protobuf.Empty | null
-          ) => {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(result);
-            }
-          }
-        );
+        client
+          .cancelOperation(
+            request,
+            undefined,
+            (
+              err?: Error | null,
+              result?: protos.google.protobuf.Empty | null,
+            ) => {
+              if (err) {
+                reject(err);
+              } else {
+                resolve(result);
+              }
+            },
+          )
+          .catch(console.error);
       });
       const response = await promise;
       assert.deepStrictEqual(response, expectedResponse);
       assert(
         (client.innerApiCalls.cancelOperation as SinonStub)
           .getCall(0)
-          .calledWith(request /* callback function above */)
+          .calledWith(request /* callback function above */),
       );
     });
 
@@ -636,15 +645,15 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
       const request = generateSampleMessage(
-        new protos.google.longrunning.CancelOperationRequest()
+        new protos.google.longrunning.CancelOperationRequest(),
       );
       const expectedError = new Error('expected');
       client.innerApiCalls.cancelOperation = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(async () => {
         await client.cancelOperation(request);
@@ -652,7 +661,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.cancelOperation as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
   });
@@ -664,14 +673,14 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.DeleteOperationRequest()
+        new protos.google.longrunning.DeleteOperationRequest(),
       );
       const expectedResponse = generateSampleMessage(
-        new protos.google.protobuf.Empty()
+        new protos.google.protobuf.Empty(),
       );
       client.innerApiCalls.deleteOperation = stubSimpleCall(expectedResponse);
       const response = await client.deleteOperation(request);
@@ -679,7 +688,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.deleteOperation as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
 
@@ -690,39 +699,41 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
 
       const request = generateSampleMessage(
-        new protos.google.longrunning.DeleteOperationRequest()
+        new protos.google.longrunning.DeleteOperationRequest(),
       );
       const expectedResponse = generateSampleMessage(
-        new protos.google.protobuf.Empty()
+        new protos.google.protobuf.Empty(),
       );
       client.innerApiCalls.deleteOperation =
         stubSimpleCallWithCallback(expectedResponse);
       const promise = new Promise((resolve, reject) => {
-        client.deleteOperation(
-          request,
-          undefined,
-          (
-            err?: Error | null,
-            result?: protos.google.protobuf.Empty | null
-          ) => {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(result);
-            }
-          }
-        );
+        client
+          .deleteOperation(
+            request,
+            undefined,
+            (
+              err?: Error | null,
+              result?: protos.google.protobuf.Empty | null,
+            ) => {
+              if (err) {
+                reject(err);
+              } else {
+                resolve(result);
+              }
+            },
+          )
+          .catch(console.error);
       });
       const response = await promise;
       assert.deepStrictEqual(response, expectedResponse);
       assert(
         (client.innerApiCalls.deleteOperation as SinonStub)
           .getCall(0)
-          .calledWith(request /* callback function above */)
+          .calledWith(request /* callback function above */),
       );
     });
 
@@ -733,15 +744,15 @@ describe('operation client', () => {
         projectId: 'bogus',
       };
       const client = new OperationsClientBuilder(grpcClient).operationsClient(
-        clientOptions
+        clientOptions,
       );
       const request = generateSampleMessage(
-        new protos.google.longrunning.DeleteOperationRequest()
+        new protos.google.longrunning.DeleteOperationRequest(),
       );
       const expectedError = new Error('expected');
       client.innerApiCalls.deleteOperation = stubSimpleCall(
         undefined,
-        expectedError
+        expectedError,
       );
       await assert.rejects(async () => {
         await client.deleteOperation(request);
@@ -749,7 +760,7 @@ describe('operation client', () => {
       assert(
         (client.innerApiCalls.deleteOperation as SinonStub)
           .getCall(0)
-          .calledWith(request)
+          .calledWith(request),
       );
     });
   });
diff --git a/gax/test/unit/pagedIteration.ts b/gax/test/unit/pagedIteration.ts
index 8399711d2..b0556d82c 100644
--- a/gax/test/unit/pagedIteration.ts
+++ b/gax/test/unit/pagedIteration.ts
@@ -17,11 +17,11 @@
 /* eslint-disable @typescript-eslint/ban-ts-comment */
 /* eslint-disable no-prototype-builtins */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import * as pumpify from 'pumpify';
 import * as sinon from 'sinon';
 import {PassThrough} from 'stream';
-import * as streamEvents from 'stream-events';
+import streamEvents from 'stream-events';
 import {PageDescriptor} from '../../src/paginationCalls/pageDescriptor';
 import {APICallback, GaxCall, RequestType} from '../../src/apitypes';
 import {describe, it, beforeEach} from 'mocha';
@@ -45,7 +45,7 @@ describe('paged iteration', () => {
     request: {pageToken?: number},
     metadata: {},
     options: {},
-    callback: APICallback
+    callback: APICallback,
   ) {
     const pageToken = request.pageToken || 0;
     if (pageToken >= pageSize * pagesToStream) {
@@ -76,8 +76,8 @@ describe('paged iteration', () => {
           warnStub.calledWith(
             'autoPaginate true',
             'Providing a pageSize without setting autoPaginate to false will still return all results. See https://github.com/googleapis/gax-nodejs/blob/main/client-libraries.md#auto-pagination for more information on how to configure manual paging',
-            'AutopaginateTrueWarning'
-          )
+            'AutopaginateTrueWarning',
+          ),
         );
         warnStub.restore();
         done();
@@ -99,16 +99,15 @@ describe('paged iteration', () => {
       .catch(done);
   });
 
-  it('calls callback with an Array', done => {
+  it('calls callback with an Array', async () => {
     const apiCall = util.createApiCall(func, createOptions);
     const expected: Array<{}> = [];
     for (let i = 0; i < pageSize * pagesToStream; ++i) {
       expected.push(i);
     }
-    apiCall({}, undefined, (err, results) => {
+    await apiCall({}, undefined, (err, results) => {
       assert.strictEqual(err, null);
       assert.deepStrictEqual(results, expected);
-      done();
     });
   });
 
@@ -147,17 +146,16 @@ describe('paged iteration', () => {
       .catch(done);
   });
 
-  it('sets additional arguments to the callback', done => {
+  it('sets additional arguments to the callback', async () => {
     let counter = 0;
     const apiCall = util.createApiCall(func, createOptions);
-    function callback(
+    async function callback(
       err: {},
       resources: {},
       next: {},
-      rawResponse: {nums: {}}
+      rawResponse: {nums: {}},
     ) {
       if (err) {
-        done(err);
         return;
       }
       counter++;
@@ -167,26 +165,29 @@ describe('paged iteration', () => {
       assert(rawResponse.hasOwnProperty('nums'));
       assert.strictEqual(rawResponse.nums, resources);
       if (next) {
-        apiCall(
+        await apiCall(
           next,
           {autoPaginate: false},
-          callback as unknown as APICallback
+          callback as unknown as APICallback,
         );
       } else {
         assert.strictEqual(counter, pagesToStream + 1);
-        done();
       }
     }
-    apiCall({}, {autoPaginate: false}, callback as unknown as APICallback);
+    await apiCall(
+      {},
+      {autoPaginate: false},
+      callback as unknown as APICallback,
+    );
   });
 
-  it('retries on failure', done => {
+  it('retries on failure', async () => {
     let callCount = 0;
     function failingFunc(
       request: {},
       metadata: {},
       options: {},
-      callback: APICallback
+      callback: APICallback,
     ) {
       callCount++;
       if (callCount % 2 === 0) {
@@ -196,14 +197,11 @@ describe('paged iteration', () => {
       }
     }
     const apiCall = util.createApiCall(failingFunc, createOptions);
-    apiCall({}, undefined)
-      .then(resources => {
-        assert(Array.isArray(resources));
-        // @ts-ignore response type
-        assert.strictEqual(resources[0].length, pageSize * pagesToStream);
-        done();
-      })
-      .catch(done);
+    await apiCall({}, undefined).then(resources => {
+      assert(Array.isArray(resources));
+      // @ts-ignore response type
+      assert.strictEqual(resources[0].length, pageSize * pagesToStream);
+    });
   });
 
   it('caps the results by maxResults', () => {
@@ -244,10 +242,10 @@ describe('paged iteration', () => {
       }
 
       const settings = new gax.CallSettings(
-        (createOptions && createOptions.settings) || {}
+        (createOptions && createOptions.settings) || {},
       );
       const resources = await iterableChecker(
-        descriptor.asyncIterate(apiCall, {}, settings)
+        descriptor.asyncIterate(apiCall, {}, settings),
       );
       assert.strictEqual(resources.length, 10);
     });
@@ -271,11 +269,11 @@ describe('paged iteration', () => {
       }
 
       const settings = new gax.CallSettings(
-        (createOptions && createOptions.settings) || {}
+        (createOptions && createOptions.settings) || {},
       );
       settings.autoPaginate = true;
       const resources = await iterableChecker(
-        descriptor.asyncIterate(apiCall, {}, settings)
+        descriptor.asyncIterate(apiCall, {}, settings),
       );
       assert.strictEqual(resources.length, 10);
       assert.strictEqual(warnStub.callCount, 1);
@@ -283,8 +281,8 @@ describe('paged iteration', () => {
         warnStub.calledWith(
           'autoPaginate true',
           'Autopaginate will always be set to false in Async paging methods. See more info at https://github.com/googleapis/gax-nodejs/blob/main/client-libraries.md#auto-pagination for more information on how to configure paging calls',
-          'AutopaginateTrueWarning'
-        )
+          'AutopaginateTrueWarning',
+        ),
       );
       warnStub.restore();
     });
@@ -293,7 +291,7 @@ describe('paged iteration', () => {
         request: {pageToken?: number},
         metadata: {},
         options: {},
-        callback: APICallback
+        callback: APICallback,
       ) {
         const responsePages = [
           [1, 2, 3],
@@ -318,7 +316,7 @@ describe('paged iteration', () => {
       }
       const apiCall = util.createApiCall(func, createOptions);
       const settings = new gax.CallSettings(
-        (createOptions && createOptions.settings) || {}
+        (createOptions && createOptions.settings) || {},
       );
       const iterable = descriptor.asyncIterate(apiCall, {}, settings);
       const results = [];
@@ -342,7 +340,7 @@ describe('paged iteration', () => {
       stream: Stream,
       onEnd: Function,
       done: (...args: string[]) => void,
-      start: number
+      start: number,
     ) {
       let counter = start;
       stream
@@ -365,7 +363,7 @@ describe('paged iteration', () => {
           assert.strictEqual(spy.callCount, pagesToStream + 1);
         },
         done,
-        0
+        0,
       );
     });
 
@@ -378,7 +376,7 @@ describe('paged iteration', () => {
         stream,
         () => assert.strictEqual(onResponse.callCount, pagesToStream + 1),
         done,
-        0
+        0,
       );
     });
 
@@ -396,7 +394,7 @@ describe('paged iteration', () => {
           assert.strictEqual(spy.callCount, 2);
         },
         done,
-        0
+        0,
       );
     });
     it('ignores autoPaginate options and warns, but respects others', done => {
@@ -415,13 +413,13 @@ describe('paged iteration', () => {
             warnStub.calledWith(
               'autoPaginate true',
               'Autopaginate will always be set to false in stream paging methods. See more info at https://github.com/googleapis/gax-nodejs/blob/main/client-libraries.md#auto-pagination for more information on how to configure paging calls',
-              'AutopaginateTrueWarning'
-            )
+              'AutopaginateTrueWarning',
+            ),
           );
           warnStub.restore();
         },
         done,
-        0
+        0,
       );
     });
     it('ignores autoPaginate options but respects others', done => {
@@ -435,7 +433,7 @@ describe('paged iteration', () => {
           assert.strictEqual(spy.callCount, 1);
         },
         done,
-        0
+        0,
       );
     });
 
@@ -454,7 +452,7 @@ describe('paged iteration', () => {
           assert.strictEqual(onResponse.callCount, spy.callCount);
         },
         done,
-        0
+        0,
       );
     });
 
@@ -469,7 +467,7 @@ describe('paged iteration', () => {
             assert.strictEqual(spy.callCount, pagesToStream + 1);
           },
           done,
-          0
+          0,
         );
       }, 50);
     });
@@ -520,7 +518,7 @@ describe('paged iteration', () => {
         request: {pageToken?: number},
         metadata: {},
         options: {},
-        callback: APICallback
+        callback: APICallback,
       ) {
         const pageToken = request.pageToken || 0;
         if (pageToken >= pageSize * pagesToStream) {
@@ -552,7 +550,7 @@ describe('paged iteration', () => {
             assert.strictEqual(onResponseSpy.callCount, spy.callCount);
           },
           done,
-          0
+          0,
         );
       });
     });
@@ -596,7 +594,7 @@ describe('REGAPIC Pagination', () => {
     request: {pageToken?: number},
     metadata: {},
     options: {},
-    callback: APICallback
+    callback: APICallback,
   ) {
     const pageToken = request.pageToken || 0;
     if (pageToken >= pageSize * pagesToStream) {
@@ -628,10 +626,10 @@ describe('REGAPIC Pagination', () => {
 
     it('return an tuple iterable, count to 10', async () => {
       const settings = new gax.CallSettings(
-        (createOptions && createOptions.settings) || {}
+        (createOptions && createOptions.settings) || {},
       );
       const resources = await iterableChecker(
-        descriptor.asyncIterate(apiCall, {}, settings)
+        descriptor.asyncIterate(apiCall, {}, settings),
       );
       assert.strictEqual(resources.length, 10);
       for await (const [key, value] of resources as [string, ResponseType]) {
diff --git a/gax/test/unit/pathTemplate.ts b/gax/test/unit/pathTemplate.ts
index 8669dada6..d06092ec6 100644
--- a/gax/test/unit/pathTemplate.ts
+++ b/gax/test/unit/pathTemplate.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {describe, it} from 'mocha';
 import {PathTemplate} from '../../src/pathTemplate';
 
@@ -102,7 +102,7 @@ describe('PathTemplate', () => {
       const want = {$0: 'hello%2F%2Bworld'};
       assert.deepStrictEqual(
         template.match('buckets/hello%2F%2Bworld/objects'),
-        want
+        want,
       );
     });
 
@@ -111,7 +111,7 @@ describe('PathTemplate', () => {
       const want = {$0: 'foo', $1: 'bar/baz'};
       assert.deepStrictEqual(
         template.match('buckets/foo/objects/bar/baz'),
-        want
+        want,
       );
     });
 
@@ -123,7 +123,7 @@ describe('PathTemplate', () => {
 
     it('should match template with non-slash resource patterns', () => {
       const template = new PathTemplate(
-        'user/{user_id}/blurbs/legacy/{blurb_a}-{blurb_b}~{legacy_user}'
+        'user/{user_id}/blurbs/legacy/{blurb_a}-{blurb_b}~{legacy_user}',
       );
       const want = {
         user_id: 'foo',
@@ -133,13 +133,13 @@ describe('PathTemplate', () => {
       };
       assert.deepStrictEqual(
         template.match('user/foo/blurbs/legacy/bara-barb~user'),
-        want
+        want,
       );
     });
 
     it('should not match template with malformed non-slash resource patterns', () => {
       const template = new PathTemplate(
-        'user/{user_id}/blurbs/legacy/{blurb_id}.{legacy_user}'
+        'user/{user_id}/blurbs/legacy/{blurb_id}.{legacy_user}',
       );
       assert.throws(() => {
         template.match('user/foo/blurbs/legacy/bar~user2');
@@ -161,7 +161,7 @@ describe('PathTemplate', () => {
     });
     it('should render atomic resource', () => {
       const template = new PathTemplate(
-        'projects/{project}/metricDescriptors/{metric_descriptor=**}'
+        'projects/{project}/metricDescriptors/{metric_descriptor=**}',
       );
       const params = {
         project: 'project-name',
@@ -203,7 +203,7 @@ describe('PathTemplate', () => {
 
     it('should accept both strings and numbers as values', () => {
       const template = new PathTemplate(
-        'projects/{project}/sessions/{session}'
+        'projects/{project}/sessions/{session}',
       );
       const params = {
         project: 'testProject',
@@ -215,7 +215,7 @@ describe('PathTemplate', () => {
 
     it('should render non-slash resource', () => {
       const template = new PathTemplate(
-        'user/{user_id}/blurbs/legacy/{blurb_id}.{legacy_user}/project/{project}'
+        'user/{user_id}/blurbs/legacy/{blurb_id}.{legacy_user}/project/{project}',
       );
       const params = {
         user_id: 'foo',
diff --git a/gax/test/unit/regapic.ts b/gax/test/unit/regapic.ts
index 6c85e75dd..0616d7cb7 100644
--- a/gax/test/unit/regapic.ts
+++ b/gax/test/unit/regapic.ts
@@ -14,9 +14,8 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {describe, it, afterEach, before} from 'mocha';
-import * as nodeFetch from 'node-fetch';
 import * as protobuf from 'protobufjs';
 import * as path from 'path';
 import * as sinon from 'sinon';
@@ -27,6 +26,7 @@ import * as transcoding from '../../src/transcoding';
 import {OAuth2Client} from 'google-auth-library';
 import {GrpcClientOptions} from '../../src';
 import {StreamArrayParser} from '../../src/streamArrayParser';
+import proxyquire from 'proxyquire';
 
 const authClient = {
   async getRequestHeaders() {
@@ -80,7 +80,7 @@ describe('REGAPIC', () => {
       '..',
       'test',
       'fixtures',
-      'library.json'
+      'library.json',
     );
     // eslint-disable-next-line @typescript-eslint/no-var-requires
     libProtos = gaxGrpc.loadProtoJSON(require(TEST_JSON));
@@ -90,33 +90,36 @@ describe('REGAPIC', () => {
   afterEach(() => {
     sinon.restore();
   });
-
-  it('should make a request', done => {
+  it('should make a request', async () => {
     const requestObject = {content: 'test-content'};
-    // incomplete types for nodeFetch, so...
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    sinon.stub(nodeFetch, 'Promise' as any).returns(
-      Promise.resolve({
-        ok: true,
-        arrayBuffer: () => {
-          return Promise.resolve(Buffer.from(JSON.stringify(requestObject)));
-        },
-      })
-    );
 
-    gaxGrpc.createStub(echoService, stubOptions).then(echoStub => {
-      echoStub.echo(requestObject, {}, {}, (err?: {}, result?: {}) => {
-        assert.strictEqual(err, null);
-        assert.strictEqual(
-          requestObject.content,
-          (result as {content: string}).content
-        );
-        done();
-      });
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.resolve({
+          ok: true,
+          arrayBuffer: () => {
+            return Promise.resolve(Buffer.from(JSON.stringify(requestObject)));
+          },
+        });
+      },
     });
+
+    const gaxGrpcMock = new GrpcClient();
+
+    (await gaxGrpcMock)
+      .createStub(echoService, stubOptions)
+      .then((echoStub: any) => {
+        echoStub.echo(requestObject, {}, {}, (err?: {}, result?: {}) => {
+          assert.strictEqual(err, null);
+          assert.strictEqual(
+            requestObject.content,
+            (result as {content: string}).content,
+          );
+        });
+      });
   });
 
-  it('should make a streaming request', done => {
+  it('should make a streaming request', async () => {
     const requestObject = {content: 'test content'};
     const responseObject = [{content: 'test'}, {content: 'content'}];
     const responseObjectJson = JSON.stringify(responseObject, null, '  ');
@@ -126,236 +129,275 @@ describe('REGAPIC', () => {
     responseStream.push(null);
     // incomplete types for nodeFetch, so...
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    sinon.stub(nodeFetch, 'Promise' as any).returns(
-      Promise.resolve({
-        ok: true,
-        body: responseStream,
-      })
-    );
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.resolve({
+          ok: true,
+          body: responseStream,
+        });
+      },
+    });
+
+    const gaxGrpcMock = new GrpcClient();
 
-    gaxGrpc.createStub(echoService, stubOptions).then(echoStub => {
+    gaxGrpcMock.createStub(echoService, stubOptions).then((echoStub: any) => {
       const stream = echoStub.expand(
         requestObject,
         {},
         {},
-        () => {}
+        () => {},
       ) as StreamArrayParser;
       const results: {}[] = [];
-      stream.on('data', data => {
+      stream.on('data', (data: {}) => {
         results.push(data);
       });
-      stream.on('error', done);
+      stream.on('error', () => {
+        return;
+      });
       stream.on('end', () => {
         assert.deepStrictEqual(results, responseObject);
-        done();
       });
     });
   });
 
-  it('should handle fetch failure', done => {
+  it('should handle fetch failure', async () => {
     const requestObject = {content: 'test-content'};
-    sinon
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      .stub(nodeFetch, 'Promise' as any)
-      .returns(Promise.reject(new Error('Fetch error')));
 
-    gaxGrpc.createStub(echoService, stubOptions).then(echoStub => {
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.reject(new Error('Fetch error'));
+      },
+    });
+
+    const gaxGrpcMock = new GrpcClient();
+
+    gaxGrpcMock.createStub(echoService, stubOptions).then((echoStub: any) => {
       echoStub.echo(requestObject, {}, {}, (err?: {}) => {
         assert.strictEqual((err as Error).message, 'Fetch error');
-        done();
       });
     });
   });
 
-  it('should handle streaming request failure', done => {
+  it('should handle streaming request failure', async () => {
     const requestObject = {content: 'test content'};
-    sinon
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      .stub(nodeFetch, 'Promise' as any)
-      .returns(Promise.reject(new Error('Fetch error')));
 
-    gaxGrpc.createStub(echoService, stubOptions).then(echoStub => {
-      const stream = echoStub.expand(requestObject) as StreamArrayParser;
-      stream.on('error', err => {
-        assert.strictEqual((err as Error).message, 'Fetch error');
-        done();
-      });
+    const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+      'node-fetch': () => {
+        return Promise.reject(new Error('Fetch error'));
+      },
     });
+
+    const gaxGrpcMock = new GrpcClient();
+    gaxGrpc
+      .createStub(echoService, stubOptions)
+      .then((echoStub: any) => {
+        const stream = echoStub.expand(requestObject) as StreamArrayParser;
+        stream.on('error', (err: Error) => {
+          assert.strictEqual((err as Error).message, 'Fetch error');
+        });
+      })
+      .catch(console.error);
   });
 
   describe('should support enum conversion in proto message', () => {
-    it('should support enum conversion in proto message response', done => {
+    it('should support enum conversion in proto message response', async () => {
       const requestObject = {name: 'shelves/shelf-name'};
       const responseObject = {
         name: 'shelf-name',
         theme: 'shelf-theme',
         type: 1,
       };
-      const spy = sinon.spy(transcoding, 'transcode');
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(responseObject)));
-          },
-        })
-      );
+      const spy = sinon.spy();
+
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(
+                Buffer.from(JSON.stringify(responseObject)),
+              );
+            },
+          });
+        },
+        '../src/transcoding.js': {transcode: spy},
+      });
 
-      gaxGrpc.createStub(libraryService, stubOptions).then(libStub => {
-        libStub.getShelf(requestObject, {}, {}, (err?: {}, result?: {}) => {
-          assert.strictEqual(spy.getCall(0).returnValue?.queryString, '');
-          assert.strictEqual(err, null);
-          assert.strictEqual(
-            'shelf-name',
-            (result as {name: {}; theme: {}; type: {}}).name
-          );
-          assert.strictEqual(
-            'TYPEONE',
-            (result as {name: {}; theme: {}; type: {}}).type
-          );
-          done();
+      const gaxGrpcMock = new GrpcClient();
+
+      gaxGrpcMock
+        .createStub(libraryService, stubOptions)
+        .then((libStub: any) => {
+          libStub.getShelf(requestObject, {}, {}, (err?: {}, result?: {}) => {
+            assert.strictEqual(spy.getCall(0).returnValue?.queryString, '');
+            assert.strictEqual(err, null);
+            assert.strictEqual(
+              'shelf-name',
+              (result as {name: {}; theme: {}; type: {}}).name,
+            );
+            assert.strictEqual(
+              'TYPEONE',
+              (result as {name: {}; theme: {}; type: {}}).type,
+            );
+          });
         });
-      }, /* catch: */ done);
     });
 
-    it('should support enum conversion in proto message request using symbolic name', done => {
+    it('should support enum conversion in proto message request using symbolic name', async () => {
       const shelf = {
         name: 'shelf-name',
         theme: 'shelf-theme',
         type: 'TYPEONE',
       };
       const requestObject = {shelf: shelf};
-      const spy = sinon.spy(transcoding, 'transcode');
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
-          },
-        })
-      );
-      gaxGrpc.createStub(libraryService, stubOptions).then(libStub => {
-        libStub.createShelf(requestObject, {}, {}, (err?: {}) => {
-          assert.strictEqual(spy.getCall(0).returnValue?.queryString, '');
-          assert.strictEqual(err, null);
-          done();
+      const spy = sinon.spy();
+
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
+            },
+          });
+        },
+        '../src/transcoding.js': {transcode: spy},
+      });
+
+      const gaxGrpcMock = new GrpcClient();
+
+      gaxGrpcMock
+        .createStub(libraryService, stubOptions)
+        .then((libStub: any) => {
+          libStub.createShelf(requestObject, {}, {}, (err?: {}) => {
+            assert.strictEqual(spy.getCall(0).returnValue?.queryString, '');
+            assert.strictEqual(err, null);
+          });
         });
-      }, /* catch: */ done);
     });
 
-    it('should support enum conversion in proto message request using type value', done => {
+    it('should support enum conversion in proto message request using type value', async () => {
       const shelf = {
         name: 'shelf-name',
         theme: 'shelf-theme',
         type: 1,
       };
       const requestObject = {shelf: shelf};
-      const spy = sinon.spy(transcoding, 'transcode');
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
-          },
-        })
-      );
-      gaxGrpc.createStub(libraryService, stubOptions).then(libStub => {
-        libStub.createShelf(requestObject, {}, {}, (err?: {}) => {
-          assert.strictEqual(spy.getCall(0).returnValue?.queryString, '');
-          assert.strictEqual(err, null);
-          done();
+      const spy = sinon.spy();
+
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
+            },
+          });
+        },
+        '../src/transcoding.js': {transcode: spy},
+      });
+
+      const gaxGrpcMock = new GrpcClient();
+      gaxGrpcMock
+        .createStub(libraryService, stubOptions)
+        .then((libStub: any) => {
+          libStub.createShelf(requestObject, {}, {}, (err?: {}) => {
+            assert.strictEqual(spy.getCall(0).returnValue?.queryString, '');
+            assert.strictEqual(err, null);
+          });
         });
-      }, /* catch: */ done);
     });
   });
 
   describe('should support enum conversion in proto message with numeric enums enabled', () => {
-    it('should support enum conversion in proto message response', done => {
+    it('should support enum conversion in proto message response', async () => {
       const requestObject = {name: 'shelves/shelf-name'};
       const responseObject = {
         name: 'shelf-name',
         theme: 'shelf-theme',
         type: 100, // unknown enum value
       };
-      const spy = sinon.spy(transcoding, 'transcode');
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(responseObject)));
-          },
-        })
-      );
+      const spy = sinon.spy();
+
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(
+                Buffer.from(JSON.stringify(responseObject)),
+              );
+            },
+          });
+        },
+        '../src/transcoding.js': {transcode: spy},
+      });
+
+      const gaxGrpcNumericEnumsMock = new GrpcClient({
+        ...opts,
+        numericEnums: true,
+      });
 
-      gaxGrpcNumericEnums
+      gaxGrpcNumericEnumsMock
         .createStub(libraryService, stubOptions)
-        .then(libStub => {
+        .then((libStub: any) => {
           libStub.getShelf(requestObject, {}, {}, (err?: {}, result?: {}) => {
             assert.strictEqual(
               spy.getCall(0).returnValue?.queryString,
-              '$alt=json%3Benum-encoding=int'
+              '$alt=json%3Benum-encoding=int',
             );
             assert.strictEqual(err, null);
             assert.strictEqual(
               'shelf-name',
-              (result as {name: {}; theme: {}; type: {}}).name
+              (result as {name: {}; theme: {}; type: {}}).name,
             );
             assert.strictEqual(
               100,
-              (result as {name: {}; theme: {}; type: {}}).type
+              (result as {name: {}; theme: {}; type: {}}).type,
             );
-            done();
           });
-        }, /* catch: */ done);
+        });
     });
 
-    it('should request numeric enums if passed as symbolic name', done => {
+    it('should request numeric enums if passed as symbolic name', async () => {
       const shelf = {
         name: 'shelf-name',
         theme: 'shelf-theme',
         type: 'TYPEONE',
       };
       const requestObject = {shelf: shelf};
-      const spy = sinon.spy(transcoding, 'transcode');
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
-          },
-        })
-      );
-      gaxGrpcNumericEnums
+      const spy = sinon.spy();
+
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
+            },
+          });
+        },
+        '../src/transcoding.js': {transcode: spy},
+      });
+
+      const gaxGrpcNumericEnumsMock = new GrpcClient({
+        ...opts,
+        numericEnums: true,
+      });
+      gaxGrpcNumericEnumsMock
         .createStub(libraryService, stubOptions)
-        .then(libStub => {
+        .then((libStub: any) => {
           libStub.createShelf(requestObject, {}, {}, (err?: {}) => {
             assert.strictEqual(
-              'string',
-              typeof spy.getCall(0).returnValue?.queryString
-            );
-            assert.match(
-              <string>spy.getCall(0).returnValue?.queryString,
-              /\$alt=json%3Benum-encoding=int(&.*)?$/
+              spy.getCall(0).returnValue?.queryString,
+              '$alt=json%3Benum-encoding=int',
             );
             assert.strictEqual(err, null);
-            done();
           });
-        }, /* catch: */ done);
+        });
     });
 
-    it('should preserve query string when appending numeric enums parameter', done => {
+    it('should preserve query string when appending numeric enums parameter', async () => {
       const shelf = {
         name: 'shelf-name',
         theme: 'shelf-theme',
@@ -365,66 +407,78 @@ describe('REGAPIC', () => {
         shelf: shelf,
         queryStringParameter: 'must-be-preserved',
       };
-      const spy = sinon.spy(transcoding, 'transcode');
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
-          },
-        })
-      );
-      gaxGrpcNumericEnums
+      const spy = sinon.spy();
+
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
+            },
+          });
+        },
+        '../src/transcoding.js': {transcode: spy},
+      });
+
+      const gaxGrpcNumericEnumsMock = new GrpcClient({
+        ...opts,
+        numericEnums: true,
+      });
+      gaxGrpcNumericEnumsMock
         .createStub(libraryService, stubOptions)
-        .then(libStub => {
+        .then((libStub: any) => {
           libStub.createShelf(requestObject, {}, {}, (err?: {}) => {
             assert.strictEqual(
               spy.getCall(0).returnValue?.queryString,
-              'queryStringParameter=must-be-preserved&$alt=json%3Benum-encoding=int'
+              'queryStringParameter=must-be-preserved&$alt=json%3Benum-encoding=int',
             );
             assert.strictEqual(err, null);
-            done();
           });
-        }, /* catch: */ done);
+        });
     });
 
-    it('should request numeric enums if passed as an unknown number', done => {
+    it('should request numeric enums if passed as an unknown number', async () => {
       const shelf = {
         name: 'shelf-name',
         theme: 'shelf-theme',
         type: 100,
       };
       const requestObject = {shelf: shelf};
-      const spy = sinon.spy(transcoding, 'transcode');
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
-          },
-        })
-      );
-      gaxGrpcNumericEnums
+      const spy = sinon.spy();
+
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(Buffer.from(JSON.stringify(shelf)));
+            },
+          });
+        },
+        '../src/transcoding.js': {transcode: spy},
+      });
+
+      const gaxGrpcNumericEnumsMock = new GrpcClient({
+        ...opts,
+        numericEnums: true,
+      });
+      gaxGrpcNumericEnumsMock
         .createStub(libraryService, stubOptions)
-        .then(libStub => {
+        .then((libStub: any) => {
           libStub.createShelf(requestObject, {}, {}, (err?: {}) => {
             assert.strictEqual(
               spy.getCall(0).returnValue?.queryString,
-              '$alt=json%3Benum-encoding=int'
+              '$alt=json%3Benum-encoding=int',
             );
             assert.strictEqual(err, null);
-            done();
           });
-        }, /* catch: */ done);
+        });
     });
   });
 
   describe('should support long data type conversion in proto message', () => {
-    it('large number long data type conversion in proto message response', done => {
+    it('large number long data type conversion in proto message response', async () => {
       const requestObject = {name: 'shelves/shelf-name/books/book-name'};
       const responseObject = {
         name: 'book-name',
@@ -433,49 +487,55 @@ describe('REGAPIC', () => {
         read: true,
         bookId: 9007199254740992,
       };
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(responseObject)));
-          },
-        })
-      );
-      gaxGrpc.createStub(libraryService, stubOptions).then(libStub => {
-        libStub.getBook(requestObject, {}, {}, (err?: {}, result?: {}) => {
-          assert.strictEqual(err, null);
-          assert.strictEqual(
-            'book-name',
-            (
-              result as {
-                name: {};
-                author: {};
-                title: {};
-                read: false;
-                bookId: {};
-              }
-            ).name
-          );
-          assert.strictEqual(
-            '9007199254740992',
-            (
-              result as {
-                name: {};
-                author: {};
-                title: {};
-                read: false;
-                bookId: {};
-              }
-            ).bookId
-          );
-          done();
+
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(
+                Buffer.from(JSON.stringify(responseObject)),
+              );
+            },
+          });
+        },
+      });
+
+      const gaxGrpcMock = new GrpcClient();
+      gaxGrpcMock
+        .createStub(libraryService, stubOptions)
+        .then((libStub: any) => {
+          libStub.getBook(requestObject, {}, {}, (err?: {}, result?: {}) => {
+            assert.strictEqual(err, null);
+            assert.strictEqual(
+              'book-name',
+              (
+                result as {
+                  name: {};
+                  author: {};
+                  title: {};
+                  read: false;
+                  bookId: {};
+                }
+              ).name,
+            );
+            assert.strictEqual(
+              '9007199254740992',
+              (
+                result as {
+                  name: {};
+                  author: {};
+                  title: {};
+                  read: false;
+                  bookId: {};
+                }
+              ).bookId,
+            );
+          });
         });
-      }, /* catch: */ done);
     });
 
-    it('small number long data type conversion in proto message response', done => {
+    it('small number long data type conversion in proto message response', async () => {
       const requestObject = {name: 'shelves/shelf-name/books/book-name'};
       const responseObject = {
         name: 'book-name',
@@ -485,48 +545,54 @@ describe('REGAPIC', () => {
         bookId: 42,
       };
       // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(responseObject)));
-          },
-        })
-      );
-      gaxGrpc.createStub(libraryService, stubOptions).then(libStub => {
-        libStub.getBook(requestObject, {}, {}, (err?: {}, result?: {}) => {
-          assert.strictEqual(err, null);
-          assert.strictEqual(
-            'book-name',
-            (
-              result as {
-                name: {};
-                author: {};
-                title: {};
-                read: false;
-                bookId: {};
-              }
-            ).name
-          );
-          assert.strictEqual(
-            '42',
-            (
-              result as {
-                name: {};
-                author: {};
-                title: {};
-                read: false;
-                bookId: {};
-              }
-            ).bookId
-          );
-          done();
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(
+                Buffer.from(JSON.stringify(responseObject)),
+              );
+            },
+          });
+        },
+      });
+
+      const gaxGrpcMock = new GrpcClient();
+      gaxGrpcMock
+        .createStub(libraryService, stubOptions)
+        .then((libStub: any) => {
+          libStub.getBook(requestObject, {}, {}, (err?: {}, result?: {}) => {
+            assert.strictEqual(err, null);
+            assert.strictEqual(
+              'book-name',
+              (
+                result as {
+                  name: {};
+                  author: {};
+                  title: {};
+                  read: false;
+                  bookId: {};
+                }
+              ).name,
+            );
+            assert.strictEqual(
+              '42',
+              (
+                result as {
+                  name: {};
+                  author: {};
+                  title: {};
+                  read: false;
+                  bookId: {};
+                }
+              ).bookId,
+            );
+          });
         });
-      }, /* catch: */ done);
     });
 
-    it('long data type conversion in proto message request', done => {
+    it('long data type conversion in proto message request', async () => {
       const bookId = 9007199254740992;
       const requestObject = {name: `shelves/shelf-name/book_id/${bookId}`};
       const responseObject = {
@@ -538,134 +604,51 @@ describe('REGAPIC', () => {
       };
       // incomplete types for nodeFetch, so...
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(responseObject)));
-          },
-        })
-      );
-      gaxGrpc.createStub(libraryService, stubOptions).then(libStub => {
-        libStub.getBook(requestObject, {}, {}, (err?: {}, result?: {}) => {
-          assert.strictEqual(err, null);
-          assert.strictEqual(
-            'book-name',
-            (
-              result as {
-                name: {};
-                author: {};
-                title: {};
-                read: false;
-                bookId: {};
-              }
-            ).name
-          );
-          assert.strictEqual(
-            bookId.toString(),
-            (
-              result as {
-                name: {};
-                author: {};
-                title: {};
-                read: false;
-                bookId: {};
-              }
-            ).bookId
-          );
-          done();
-        });
-      }, /* catch: */ done);
-    });
-  });
-
-  describe('should support json minification', () => {
-    it('should send prettyPrint=0 when json minification is requested', done => {
-      const requestObject = {name: 'shelves/shelf-name'};
-      const responseObject = {
-        name: 'shelf-name',
-        theme: 'shelf-theme',
-        type: 100, // unknown enum value
-      };
-      const spy = sinon.spy(transcoding, 'transcode');
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(responseObject)));
-          },
-        })
-      );
+      const {GrpcClient} = await proxyquire('../../src/fallback.js', {
+        'node-fetch': () => {
+          return Promise.resolve({
+            ok: true,
+            arrayBuffer: () => {
+              return Promise.resolve(
+                Buffer.from(JSON.stringify(responseObject)),
+              );
+            },
+          });
+        },
+      });
 
-      gaxGrpcMinifyJson
+      const gaxGrpcMock = new GrpcClient();
+      gaxGrpcMock
         .createStub(libraryService, stubOptions)
-        .then(libStub => {
-          libStub.getShelf(requestObject, {}, {}, (err?: {}, result?: {}) => {
-            assert.strictEqual(
-              'string',
-              typeof spy.getCall(0).returnValue?.queryString
-            );
-            assert.match(
-              <string>spy.getCall(0).returnValue?.queryString,
-              /\$prettyPrint=0(&.*)?$/
-            );
+        .then((libStub: any) => {
+          libStub.getBook(requestObject, {}, {}, (err?: {}, result?: {}) => {
             assert.strictEqual(err, null);
             assert.strictEqual(
-              'shelf-name',
-              (result as {name: {}; theme: {}; type: {}}).name
+              'book-name',
+              (
+                result as {
+                  name: {};
+                  author: {};
+                  title: {};
+                  read: false;
+                  bookId: {};
+                }
+              ).name,
             );
             assert.strictEqual(
-              100,
-              (result as {name: {}; theme: {}; type: {}}).type
+              bookId.toString(),
+              (
+                result as {
+                  name: {};
+                  author: {};
+                  title: {};
+                  read: false;
+                  bookId: {};
+                }
+              ).bookId,
             );
-            done();
           });
-        }, /* catch: */ done);
-    });
-
-    it('should not send prettyPrint setting when json minification is not requested', done => {
-      const requestObject = {name: 'shelves/shelf-name'};
-      const responseObject = {
-        name: 'shelf-name',
-        theme: 'shelf-theme',
-        type: 100, // unknown enum value
-      };
-      const spy = sinon.spy(transcoding, 'transcode');
-      // incomplete types for nodeFetch, so...
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      sinon.stub(nodeFetch, 'Promise' as any).returns(
-        Promise.resolve({
-          ok: true,
-          arrayBuffer: () => {
-            return Promise.resolve(Buffer.from(JSON.stringify(responseObject)));
-          },
-        })
-      );
-
-      gaxGrpc.createStub(libraryService, stubOptions).then(libStub => {
-        libStub.getShelf(requestObject, {}, {}, (err?: {}, result?: {}) => {
-          assert.strictEqual(
-            'string',
-            typeof spy.getCall(0).returnValue?.queryString
-          );
-          assert.doesNotMatch(
-            <string>spy.getCall(0).returnValue?.queryString,
-            /prettyPrint/
-          );
-          assert.strictEqual(err, null);
-          assert.strictEqual(
-            'shelf-name',
-            (result as {name: {}; theme: {}; type: {}}).name
-          );
-          assert.strictEqual(
-            100,
-            (result as {name: {}; theme: {}; type: {}}).type
-          );
-          done();
         });
-      }, /* catch: */ done);
     });
   });
 });
diff --git a/gax/test/unit/routingHeader.ts b/gax/test/unit/routingHeader.ts
index a1e318830..1e7c77f83 100644
--- a/gax/test/unit/routingHeader.ts
+++ b/gax/test/unit/routingHeader.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {fromParams} from '../../src/routingHeader';
 import {describe, it} from 'mocha';
 
@@ -28,7 +28,7 @@ describe('fromParams', () => {
     const routingHeader = fromParams({screaming: '😱', cyrillic: 'тест'});
     assert.strictEqual(
       routingHeader,
-      'screaming=%F0%9F%98%B1&cyrillic=%D1%82%D0%B5%D1%81%D1%82'
+      'screaming=%F0%9F%98%B1&cyrillic=%D1%82%D0%B5%D1%81%D1%82',
     );
   });
 });
diff --git a/gax/test/unit/status.ts b/gax/test/unit/status.ts
index 3007be4dc..1302e2c28 100644
--- a/gax/test/unit/status.ts
+++ b/gax/test/unit/status.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {describe, it} from 'mocha';
 import {rpcCodeFromHttpStatusCode, Status} from '../../src/status';
 
@@ -26,40 +26,40 @@ describe('status.ts', () => {
     assert.deepStrictEqual(rpcCodeFromHttpStatusCode(307), Status.UNKNOWN);
     assert.deepStrictEqual(
       rpcCodeFromHttpStatusCode(400),
-      Status.INVALID_ARGUMENT
+      Status.INVALID_ARGUMENT,
     );
     assert.deepStrictEqual(
       rpcCodeFromHttpStatusCode(401),
-      Status.UNAUTHENTICATED
+      Status.UNAUTHENTICATED,
     );
     assert.deepStrictEqual(
       rpcCodeFromHttpStatusCode(403),
-      Status.PERMISSION_DENIED
+      Status.PERMISSION_DENIED,
     );
     assert.deepStrictEqual(rpcCodeFromHttpStatusCode(404), Status.NOT_FOUND);
     assert.deepStrictEqual(rpcCodeFromHttpStatusCode(409), Status.ABORTED);
     assert.deepStrictEqual(rpcCodeFromHttpStatusCode(416), Status.OUT_OF_RANGE);
     assert.deepStrictEqual(
       rpcCodeFromHttpStatusCode(429),
-      Status.RESOURCE_EXHAUSTED
+      Status.RESOURCE_EXHAUSTED,
     );
     assert.deepStrictEqual(rpcCodeFromHttpStatusCode(499), Status.CANCELLED);
     assert.deepStrictEqual(
       rpcCodeFromHttpStatusCode(451),
-      Status.FAILED_PRECONDITION
+      Status.FAILED_PRECONDITION,
     );
     assert.deepStrictEqual(
       rpcCodeFromHttpStatusCode(411),
-      Status.FAILED_PRECONDITION
+      Status.FAILED_PRECONDITION,
     );
     assert.deepStrictEqual(
       rpcCodeFromHttpStatusCode(501),
-      Status.UNIMPLEMENTED
+      Status.UNIMPLEMENTED,
     );
     assert.deepStrictEqual(rpcCodeFromHttpStatusCode(503), Status.UNAVAILABLE);
     assert.deepStrictEqual(
       rpcCodeFromHttpStatusCode(504),
-      Status.DEADLINE_EXCEEDED
+      Status.DEADLINE_EXCEEDED,
     );
     assert.deepStrictEqual(rpcCodeFromHttpStatusCode(505), Status.INTERNAL);
     assert.deepStrictEqual(rpcCodeFromHttpStatusCode(510), Status.INTERNAL);
diff --git a/gax/test/unit/streamArrayParser.ts b/gax/test/unit/streamArrayParser.ts
index 61325031b..ca9da211b 100644
--- a/gax/test/unit/streamArrayParser.ts
+++ b/gax/test/unit/streamArrayParser.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {StreamArrayParser} from '../../src/streamArrayParser';
 import {before, describe, it} from 'mocha';
 import {pipeline} from 'stream';
@@ -102,7 +102,7 @@ describe('Parse REST stream array', () => {
       },
     ];
     const inStream = createRandomChunkReadableStream(
-      JSON.stringify(expectedResults)
+      JSON.stringify(expectedResults),
     );
     inStream.on('data', d => {
       assert.notEqual(d, undefined);
@@ -125,7 +125,7 @@ describe('Parse REST stream array', () => {
         const expect = toProtobufJSON(User, expectedResults[key]);
         assert.strictEqual(
           JSON.stringify(results[key]),
-          JSON.stringify(expect)
+          JSON.stringify(expect),
         );
       }
       done();
@@ -143,7 +143,7 @@ describe('Parse REST stream array', () => {
       },
     ];
     const inStream = createRandomChunkReadableStream(
-      JSON.stringify(expectedResults)
+      JSON.stringify(expectedResults),
     );
     const streamArrayParser = new StreamArrayParser(streamMethod);
     pipeline(inStream, streamArrayParser, err => {
@@ -165,7 +165,7 @@ describe('Parse REST stream array', () => {
   it("should listen on error if input stream is not start '['", done => {
     const expectedResults = {};
     const inStream = createRandomChunkReadableStream(
-      JSON.stringify(expectedResults)
+      JSON.stringify(expectedResults),
     );
     const streamArrayParser = new StreamArrayParser(streamMethod);
     pipeline(inStream, streamArrayParser, err => {
diff --git a/gax/test/unit/streaming.ts b/gax/test/unit/streaming.ts
index 4c291abe9..5aa3512a1 100644
--- a/gax/test/unit/streaming.ts
+++ b/gax/test/unit/streaming.ts
@@ -16,7 +16,7 @@
 
 /* eslint-disable @typescript-eslint/ban-ts-comment */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import * as sinon from 'sinon';
 import {afterEach, describe, it} from 'mocha';
 import {PassThrough, Transform, pipeline} from 'stream';
@@ -47,14 +47,14 @@ function createApiCallStreaming(
     | sinon.SinonSpy<Array<{}>, internal.Transform | StreamArrayParser>,
   type: streaming.StreamType,
   rest?: boolean,
-  gaxStreamingRetries?: boolean
+  gaxStreamingRetries?: boolean,
 ) {
   const settings = new gax.CallSettings();
   return createApiCall(
     //@ts-ignore
     Promise.resolve(func),
     settings,
-    new StreamDescriptor(type, rest, gaxStreamingRetries)
+    new StreamDescriptor(type, rest, gaxStreamingRetries),
   ) as GaxCallStream;
 }
 
@@ -80,7 +80,7 @@ describe('streaming', () => {
 
     const apiCall = createApiCallStreaming(
       spy,
-      streaming.StreamType.SERVER_STREAMING
+      streaming.StreamType.SERVER_STREAMING,
     );
     const s = apiCall({}, undefined);
     const callback = sinon.spy(data => {
@@ -119,7 +119,7 @@ describe('streaming', () => {
     const apiCall = createApiCallStreaming(
       //@ts-ignore
       func,
-      streaming.StreamType.CLIENT_STREAMING
+      streaming.StreamType.CLIENT_STREAMING,
     );
     const s = apiCall({}, undefined, (err, response) => {
       assert.strictEqual(err, null);
@@ -148,7 +148,7 @@ describe('streaming', () => {
     const apiCall = createApiCallStreaming(
       //@ts-ignore
       func,
-      streaming.StreamType.BIDI_STREAMING
+      streaming.StreamType.BIDI_STREAMING,
     );
     const s = apiCall({}, undefined);
     const arg = {foo: 'bar'};
@@ -191,7 +191,7 @@ describe('streaming', () => {
     const apiCall = createApiCallStreaming(
       //@ts-ignore
       func,
-      streaming.StreamType.BIDI_STREAMING
+      streaming.StreamType.BIDI_STREAMING,
     );
     const s = apiCall({}, undefined);
     let receivedMetadata: {};
@@ -266,7 +266,7 @@ describe('streaming', () => {
     const apiCall = createApiCallStreaming(
       //@ts-ignore
       func,
-      streaming.StreamType.SERVER_STREAMING
+      streaming.StreamType.SERVER_STREAMING,
     );
     const s = apiCall(
       {},
@@ -279,7 +279,7 @@ describe('streaming', () => {
           maxRpcTimeoutMillis: 3000,
           maxRetries: 0,
         }),
-      }
+      },
     );
     let counter = 0;
     const expectedCount = 5;
@@ -331,7 +331,7 @@ describe('streaming', () => {
       func,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // gax native retries
+      true, // gax native retries
     );
     const s = apiCall(
       {},
@@ -344,7 +344,7 @@ describe('streaming', () => {
           maxRpcTimeoutMillis: 3000,
           maxRetries: 0,
         }),
-      }
+      },
     );
     let counter = 0;
     const expectedCount = 5;
@@ -393,7 +393,7 @@ describe('streaming', () => {
 
     const apiCall = createApiCallStreaming(
       spy,
-      streaming.StreamType.SERVER_STREAMING
+      streaming.StreamType.SERVER_STREAMING,
     );
     const s = apiCall({}, undefined);
     let receivedMetadata: {};
@@ -473,7 +473,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new gax retries
+      true, // new gax retries
     );
     const s = apiCall({}, undefined);
     let receivedMetadata: {};
@@ -547,7 +547,7 @@ describe('streaming', () => {
 
     const apiCall = createApiCallStreaming(
       spy,
-      streaming.StreamType.SERVER_STREAMING
+      streaming.StreamType.SERVER_STREAMING,
     );
     const s = apiCall({}, undefined);
     let receivedStatus: {};
@@ -615,7 +615,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new gax retries
+      true, // new gax retries
     );
     const s = apiCall({}, undefined);
     let receivedStatus: {};
@@ -702,7 +702,7 @@ describe('streaming', () => {
     });
     const apiCall = createApiCallStreaming(
       spy,
-      streaming.StreamType.SERVER_STREAMING
+      streaming.StreamType.SERVER_STREAMING,
     );
 
     const s = apiCall(
@@ -716,7 +716,7 @@ describe('streaming', () => {
           maxRpcTimeoutMillis: 3000,
           maxRetries: 0,
         }),
-      }
+      },
     );
 
     s.on('error', err => {
@@ -728,7 +728,7 @@ describe('streaming', () => {
       assert.strictEqual(err.reason, errorInfoObj.reason);
       assert.strictEqual(
         JSON.stringify(err.errorInfoMetadata),
-        JSON.stringify(errorInfoObj.metadata)
+        JSON.stringify(errorInfoObj.metadata),
       );
       done();
     });
@@ -783,7 +783,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new retry behavior enabled
+      true, // new retry behavior enabled
     );
 
     const s = apiCall(
@@ -797,7 +797,7 @@ describe('streaming', () => {
           maxRpcTimeoutMillis: 3000,
           maxRetries: 0,
         }),
-      }
+      },
     );
 
     s.on('error', err => {
@@ -809,7 +809,7 @@ describe('streaming', () => {
       assert.strictEqual(err.reason, errorInfoObj.reason);
       assert.strictEqual(
         JSON.stringify(err.errorInfoMetadata),
-        JSON.stringify(errorInfoObj.metadata)
+        JSON.stringify(errorInfoObj.metadata),
       );
       done();
     });
@@ -865,7 +865,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new retry behavior enabled
+      true, // new retry behavior enabled
     );
 
     const s = apiCall(
@@ -879,7 +879,7 @@ describe('streaming', () => {
           maxRpcTimeoutMillis: 3000,
           maxRetries: 1, // max retries or timeout must be > 0 in order to reach the code we want to test
         }),
-      }
+      },
     );
 
     s.on('error', err => {
@@ -890,13 +890,13 @@ describe('streaming', () => {
       assert.deepStrictEqual(err.message, 'test error');
       assert.deepStrictEqual(
         err.note,
-        'Exception occurred in retry method that was not classified as transient'
+        'Exception occurred in retry method that was not classified as transient',
       );
       assert.strictEqual(err.domain, errorInfoObj.domain);
       assert.strictEqual(err.reason, errorInfoObj.reason);
       assert.strictEqual(
         JSON.stringify(err.errorInfoMetadata),
-        JSON.stringify(errorInfoObj.metadata)
+        JSON.stringify(errorInfoObj.metadata),
       );
       done();
     });
@@ -950,7 +950,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new retry behavior enabled
+      true, // new retry behavior enabled
     );
 
     const s = apiCall(
@@ -964,7 +964,7 @@ describe('streaming', () => {
           maxRpcTimeoutMillis: 3000,
           // neither maxRetries nor totalTimeoutMillis is defined
         }),
-      }
+      },
     );
 
     s.on('error', err => {
@@ -975,13 +975,13 @@ describe('streaming', () => {
       assert.deepStrictEqual(err.message, 'test error');
       assert.deepStrictEqual(
         err.note,
-        'Exception occurred in retry method that was not classified as transient'
+        'Exception occurred in retry method that was not classified as transient',
       );
       assert.strictEqual(err.domain, errorInfoObj.domain);
       assert.strictEqual(err.reason, errorInfoObj.reason);
       assert.strictEqual(
         JSON.stringify(err.errorInfoMetadata),
-        JSON.stringify(errorInfoObj.metadata)
+        JSON.stringify(errorInfoObj.metadata),
       );
       done();
     });
@@ -1074,7 +1074,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new retry behavior enabled
+      true, // new retry behavior enabled
     );
     const s = apiCall(
       {},
@@ -1087,7 +1087,7 @@ describe('streaming', () => {
           maxRpcTimeoutMillis: 3000,
           maxRetries: 2, // max retries or timeout must be > 0 in order to reach the code we want to test
         }),
-      }
+      },
     );
 
     s.on('error', err => {
@@ -1097,13 +1097,13 @@ describe('streaming', () => {
       assert.deepStrictEqual(err.message, 'test error 2');
       assert.deepStrictEqual(
         err.note,
-        'Exception occurred in retry method that was not classified as transient'
+        'Exception occurred in retry method that was not classified as transient',
       );
       assert.strictEqual(err.domain, errorInfoObj.domain);
       assert.strictEqual(err.reason, errorInfoObj.reason);
       assert.strictEqual(
         JSON.stringify(err.errorInfoMetadata),
-        JSON.stringify(errorInfoObj.metadata)
+        JSON.stringify(errorInfoObj.metadata),
       );
       done();
     });
@@ -1138,7 +1138,7 @@ describe('streaming', () => {
             counter++;
             assert.deepStrictEqual(
               receivedData.join(' '),
-              'Hello World testing retries'
+              'Hello World testing retries',
             );
             done();
             break;
@@ -1153,7 +1153,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // streaming retries
+      true, // streaming retries
     );
 
     const s = apiCall(
@@ -1167,7 +1167,7 @@ describe('streaming', () => {
           maxRpcTimeoutMillis: 3000,
           maxRetries: 1,
         }),
-      }
+      },
     );
     s.on('data', data => {
       receivedData.push(data);
@@ -1230,7 +1230,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new retries
+      true, // new retries
     );
 
     function shouldRetryFn(error: GoogleError) {
@@ -1249,9 +1249,9 @@ describe('streaming', () => {
             maxRpcTimeoutMillis: 3000,
             maxRetries: 2, // maxRetries must be > 1 to ensure we hit both checks for a shouldRetry function
           },
-          shouldRetryFn
+          shouldRetryFn,
         ),
-      }
+      },
     );
     const finalData: string[] = [];
     s.on('data', data => {
@@ -1334,7 +1334,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new retry behavior enabled
+      true, // new retry behavior enabled
     );
     // resumption strategy is to pass a different arg to the function
     const getResumptionRequestFn = sinon.spy((originalRequest: RequestType) => {
@@ -1355,9 +1355,9 @@ describe('streaming', () => {
             maxRetries: 2, // max retries or timeout must be > 0 in order to reach the code we want to test
           },
           undefined,
-          getResumptionRequestFn
+          getResumptionRequestFn,
         ),
-      }
+      },
     );
     s.on('data', data => {
       receivedData.push(data);
@@ -1372,7 +1372,7 @@ describe('streaming', () => {
       assert.strictEqual(receivedData.length, 4);
       assert.deepStrictEqual(
         receivedData.join(' '),
-        'Hello World testing retries'
+        'Hello World testing retries',
       );
       assert.strictEqual(getResumptionRequestFn.callCount, 1);
       done();
@@ -1438,7 +1438,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      false // new retry behavior disabled
+      false, // new retry behavior disabled
     );
     // resumption strategy is to pass a different arg to the function
     const getResumptionRequestFn = (originalRequest: RequestType) => {
@@ -1459,9 +1459,9 @@ describe('streaming', () => {
             maxRetries: 2, // max retries or timeout must be > 0 in order to reach the code we want to test
           },
           undefined,
-          getResumptionRequestFn
+          getResumptionRequestFn,
         ),
-      }
+      },
     );
 
     s.on('error', err => {
@@ -1469,7 +1469,7 @@ describe('streaming', () => {
       // stream will continue after retry
       assert.deepStrictEqual(
         err.message,
-        'getResumptionRequestFn can only be used when gaxStreamingRetries is set to true.'
+        'getResumptionRequestFn can only be used when gaxStreamingRetries is set to true.',
       );
       done();
     });
@@ -1498,7 +1498,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new retry behavior enabled
+      true, // new retry behavior enabled
     );
     const s1 = apiCall({}, undefined);
 
@@ -1508,7 +1508,7 @@ describe('streaming', () => {
       transform: (data, _encoding, callback) => {
         callback(
           null,
-          data.resources.map((element: number) => element + 1)
+          data.resources.map((element: number) => element + 1),
         );
       },
     });
@@ -1526,7 +1526,7 @@ describe('streaming', () => {
     s2.on('end', () => {
       assert.strictEqual(
         JSON.stringify(finalResults),
-        JSON.stringify([[2, 3]])
+        JSON.stringify([[2, 3]]),
       );
       done();
     });
@@ -1534,7 +1534,7 @@ describe('streaming', () => {
     pipeline(s1, transform, s2, err => {
       if (err) {
         throw new Error(
-          'pipeline in properly emits the end event at the end of a pipeline transformation test failed'
+          'pipeline in properly emits the end event at the end of a pipeline transformation test failed',
         );
       }
     });
@@ -1563,7 +1563,7 @@ describe('streaming', () => {
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // new retry behavior enabled
+      true, // new retry behavior enabled
     );
     const s1 = apiCall({}, undefined);
 
@@ -1574,7 +1574,7 @@ describe('streaming', () => {
         setTimeout(() => {
           callback(
             null,
-            data.resources.map((element: number) => element + 1)
+            data.resources.map((element: number) => element + 1),
           );
         }, 10);
       },
@@ -1593,7 +1593,7 @@ describe('streaming', () => {
     s2.on('end', () => {
       assert.strictEqual(
         JSON.stringify(finalResults),
-        JSON.stringify([[2, 3]])
+        JSON.stringify([[2, 3]]),
       );
       done();
     });
@@ -1601,7 +1601,7 @@ describe('streaming', () => {
     pipeline(s1, transform, s2, err => {
       if (err) {
         throw new Error(
-          'pipeline in properly emits the end event at the end of a pipeline transformation test failed'
+          'pipeline in properly emits the end event at the end of a pipeline transformation test failed',
         );
       }
     });
@@ -1615,7 +1615,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
   it('server streaming call retries until exceeding timeout and surfaces underlying error', done => {
     const retrySpy = sinon.spy(
       streaming.StreamProxy.prototype,
-      'throwIfMaxRetriesOrTotalTimeoutExceeded'
+      'throwIfMaxRetriesOrTotalTimeoutExceeded',
     );
     const firstError = Object.assign(new GoogleError('UNAVAILABLE'), {
       code: 14,
@@ -1641,7 +1641,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true
+      true,
     );
 
     const call = apiCall(
@@ -1655,7 +1655,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           maxRpcTimeoutMillis: 3000,
           totalTimeoutMillis: 200, // timeout that ensures it should retry at least once
         }),
-      }
+      },
     );
 
     call.on('error', err => {
@@ -1667,7 +1667,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           assert.notStrictEqual(retrySpy.callCount, 0); // it MUST retry at least once
           assert.strictEqual(
             err.message,
-            'Total timeout of API exceeded 200 milliseconds retrying error Error: UNAVAILABLE  before any response was received.'
+            'Total timeout of API exceeded 200 milliseconds retrying error Error: UNAVAILABLE  before any response was received.',
           );
           done();
         }
@@ -1680,7 +1680,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
   it('server streaming call retries until exceeding max retries and surfaces underlying error in note', done => {
     const retrySpy = sinon.spy(
       streaming.StreamProxy.prototype,
-      'throwIfMaxRetriesOrTotalTimeoutExceeded'
+      'throwIfMaxRetriesOrTotalTimeoutExceeded',
     );
     const firstError = Object.assign(new GoogleError('UNAVAILABLE'), {
       code: 14,
@@ -1706,7 +1706,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true
+      true,
     );
 
     const call = apiCall(
@@ -1720,7 +1720,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           maxRpcTimeoutMillis: 3000,
           maxRetries: 2,
         }),
-      }
+      },
     );
 
     call.on('error', err => {
@@ -1732,7 +1732,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           assert.strictEqual(retrySpy.callCount, 3); // we pass the first two times
           assert.strictEqual(
             err.message,
-            'Exceeded maximum number of retries retrying error Error: UNAVAILABLE before any response was received'
+            'Exceeded maximum number of retries retrying error Error: UNAVAILABLE before any response was received',
           );
           done();
         }
@@ -1746,7 +1746,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
     // we don't call the timeout/max retry check on non retryable error codes
     const retrySpy = sinon.spy(
       streaming.StreamProxy.prototype,
-      'throwIfMaxRetriesOrTotalTimeoutExceeded'
+      'throwIfMaxRetriesOrTotalTimeoutExceeded',
     );
     const firstError = Object.assign(new GoogleError('UNAVAILABLE'), {
       code: 14,
@@ -1773,7 +1773,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true
+      true,
     );
 
     const call = apiCall(
@@ -1788,7 +1788,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           maxRpcTimeoutMillis: 3000,
           maxRetries: 2,
         }),
-      }
+      },
     );
 
     call.on('error', err => {
@@ -1827,7 +1827,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true
+      true,
     );
 
     const call = apiCall(
@@ -1841,7 +1841,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           maxRpcTimeoutMillis: 3000,
           totalTimeoutMillis: 10,
         }),
-      }
+      },
     );
 
     call.on('error', err => {
@@ -1851,7 +1851,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
         assert.strictEqual(err.code, 4);
         assert.strictEqual(
           err.message,
-          'Total timeout of API exceeded 10 milliseconds retrying error Error: UNAVAILABLE  before any response was received.'
+          'Total timeout of API exceeded 10 milliseconds retrying error Error: UNAVAILABLE  before any response was received.',
         );
         done();
       }
@@ -1877,7 +1877,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true //gaxStreamingRetries
+      true, //gaxStreamingRetries
     );
 
     // anonymous function is a shouldRetryFn
@@ -1896,9 +1896,9 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           },
           () => {
             return true;
-          }
+          },
         ),
-      }
+      },
     );
   });
 
@@ -1921,7 +1921,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true //gaxStreamingRetries
+      true, //gaxStreamingRetries
     );
 
     apiCall(
@@ -1935,7 +1935,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           maxRpcTimeoutMillis: 3000,
           totalTimeoutMillis: 4500,
         }),
-      }
+      },
     );
   });
 
@@ -1967,7 +1967,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true //gaxStreamingRetries
+      true, //gaxStreamingRetries
     );
 
     // "resumption" strategy is to just return the original request
@@ -1989,9 +1989,9 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
             totalTimeoutMillis: 4500,
           },
           undefined,
-          getResumptionRequestFn
+          getResumptionRequestFn,
         ),
-      }
+      },
     );
   });
 
@@ -2025,7 +2025,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // ensure we're doing the new retries
+      true, // ensure we're doing the new retries
     );
 
     // make the call with both options passed at call time
@@ -2041,7 +2041,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           totalTimeoutMillis: 4000,
           maxRetries: 5,
         }),
-      }
+      },
     );
     call.on('error', err => {
       assert(err instanceof GoogleError);
@@ -2049,7 +2049,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
         assert.strictEqual(err.code, 3);
         assert.strictEqual(
           err.message,
-          'Cannot set both totalTimeoutMillis and maxRetries in backoffSettings.'
+          'Cannot set both totalTimeoutMillis and maxRetries in backoffSettings.',
         );
         done();
       }
@@ -2074,7 +2074,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // ensure we're doing the new retries
+      true, // ensure we're doing the new retries
     );
 
     const passedRetryRequestOptions = {
@@ -2103,13 +2103,13 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
             maxRpcTimeoutMillis: 3000,
             totalTimeoutMillis: 4500,
           }),
-        }
+        },
       );
     } catch (err) {
       assert(err instanceof Error);
       assert.strictEqual(
         err.toString(),
-        'Error: Only one of retry or retryRequestOptions may be set'
+        'Error: Only one of retry or retryRequestOptions may be set',
       );
       done();
     }
@@ -2128,16 +2128,16 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           assert(typeof settings.retryRequestOptions === 'undefined');
           assert.strictEqual(
             settings.retry?.backoffSettings.maxRetryDelayMillis,
-            70000
+            70000,
           );
           assert.strictEqual(
             settings.retry?.backoffSettings.retryDelayMultiplier,
-            3
+            3,
           );
           // totalTimeout is undefined because maxRetries is passed
           assert(
             typeof settings.retry?.backoffSettings.totalTimeoutMillis ===
-              'undefined'
+              'undefined',
           );
 
           assert.strictEqual(settings.retry?.backoffSettings.maxRetries, 1);
@@ -2162,7 +2162,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // gaxStreamingRetries
+      true, // gaxStreamingRetries
     );
     const passedRetryRequestOptions = {
       objectMode: false,
@@ -2180,7 +2180,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       {},
       {
         retryRequestOptions: passedRetryRequestOptions,
-      }
+      },
     );
 
     assert.strictEqual(warnStub.callCount, 4);
@@ -2188,29 +2188,29 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       warnStub.calledWith(
         'retry_request_options',
         'retryRequestOptions will be deprecated in a future release. Please use retryOptions to pass retry options at call time',
-        'DeprecationWarning'
-      )
+        'DeprecationWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'noResponseRetries override is not supported. Please specify retry codes or a function to determine retry eligibility.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'currentRetryAttempt override is not supported. Retry attempts are tracked internally.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'objectMode override is not supported. It is set to true internally by default in gax.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
   });
 
@@ -2227,16 +2227,16 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           assert(typeof settings.retryRequestOptions === 'undefined');
           assert.strictEqual(
             settings.retry?.backoffSettings.maxRetryDelayMillis,
-            0
+            0,
           );
           assert.strictEqual(
             settings.retry?.backoffSettings.retryDelayMultiplier,
-            0
+            0,
           );
           // totalTimeout is undefined because maxRetries is passed
           assert(
             typeof settings.retry?.backoffSettings.totalTimeoutMillis ===
-              'undefined'
+              'undefined',
           );
 
           assert.strictEqual(settings.retry?.backoffSettings.maxRetries, 0);
@@ -2261,7 +2261,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // gaxStreamingRetries
+      true, // gaxStreamingRetries
     );
     const passedRetryRequestOptions = {
       objectMode: false,
@@ -2279,7 +2279,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       {},
       {
         retryRequestOptions: passedRetryRequestOptions,
-      }
+      },
     );
 
     assert.strictEqual(warnStub.callCount, 4);
@@ -2287,29 +2287,29 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       warnStub.calledWith(
         'retry_request_options',
         'retryRequestOptions will be deprecated in a future release. Please use retryOptions to pass retry options at call time',
-        'DeprecationWarning'
-      )
+        'DeprecationWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'noResponseRetries override is not supported. Please specify retry codes or a function to determine retry eligibility.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'currentRetryAttempt override is not supported. Retry attempts are tracked internally.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'objectMode override is not supported. It is set to true internally by default in gax.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
   });
 
@@ -2326,18 +2326,18 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           assert(typeof settings.retryRequestOptions === 'undefined');
           assert.strictEqual(
             settings.retry?.backoffSettings.maxRetryDelayMillis,
-            70000
+            70000,
           );
           assert.strictEqual(
             settings.retry?.backoffSettings.retryDelayMultiplier,
-            3
+            3,
           );
           assert.strictEqual(
             settings.retry?.backoffSettings.totalTimeoutMillis,
-            650000
+            650000,
           );
           assert(
-            typeof settings.retry?.backoffSettings.maxRetries === 'undefined'
+            typeof settings.retry?.backoffSettings.maxRetries === 'undefined',
           );
           assert(settings.retry.shouldRetryFn);
           assert(settings.retry.retryCodes.length === 0);
@@ -2360,7 +2360,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // gaxStreamingRetries
+      true, // gaxStreamingRetries
     );
     const passedRetryRequestOptions = {
       objectMode: false,
@@ -2377,7 +2377,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       {},
       {
         retryRequestOptions: passedRetryRequestOptions,
-      }
+      },
     );
 
     assert.strictEqual(warnStub.callCount, 4);
@@ -2385,29 +2385,29 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       warnStub.calledWith(
         'retry_request_options',
         'retryRequestOptions will be deprecated in a future release. Please use retryOptions to pass retry options at call time',
-        'DeprecationWarning'
-      )
+        'DeprecationWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'objectMode override is not supported. It is set to true internally by default in gax.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'noResponseRetries override is not supported. Please specify retry codes or a function to determine retry eligibility.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'currentRetryAttempt override is not supported. Retry attempts are tracked internally.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
   });
 
@@ -2424,18 +2424,18 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
           assert(typeof settings.retryRequestOptions === 'undefined');
           assert.strictEqual(
             settings.retry?.backoffSettings.maxRetryDelayMillis,
-            0
+            0,
           );
           assert.strictEqual(
             settings.retry?.backoffSettings.retryDelayMultiplier,
-            0
+            0,
           );
           assert.strictEqual(
             settings.retry?.backoffSettings.totalTimeoutMillis,
-            0
+            0,
           );
           assert(
-            typeof settings.retry?.backoffSettings.maxRetries === 'undefined'
+            typeof settings.retry?.backoffSettings.maxRetries === 'undefined',
           );
           assert(settings.retry.shouldRetryFn);
           assert(settings.retry.retryCodes.length === 0);
@@ -2458,7 +2458,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      true // gaxStreamingRetries
+      true, // gaxStreamingRetries
     );
     const passedRetryRequestOptions = {
       objectMode: false,
@@ -2475,7 +2475,7 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       {},
       {
         retryRequestOptions: passedRetryRequestOptions,
-      }
+      },
     );
 
     assert.strictEqual(warnStub.callCount, 4);
@@ -2483,29 +2483,29 @@ describe('handles server streaming retries in gax when gaxStreamingRetries is en
       warnStub.calledWith(
         'retry_request_options',
         'retryRequestOptions will be deprecated in a future release. Please use retryOptions to pass retry options at call time',
-        'DeprecationWarning'
-      )
+        'DeprecationWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'objectMode override is not supported. It is set to true internally by default in gax.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'noResponseRetries override is not supported. Please specify retry codes or a function to determine retry eligibility.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
     assert(
       warnStub.calledWith(
         'retry_request_options',
         'currentRetryAttempt override is not supported. Retry attempts are tracked internally.',
-        'UnsupportedParameterWarning'
-      )
+        'UnsupportedParameterWarning',
+      ),
     );
   });
 });
@@ -2535,7 +2535,7 @@ describe('warns/errors about server streaming retry behavior when gaxStreamingRe
       spy,
       streaming.StreamType.SERVER_STREAMING,
       false,
-      false // ensure we are NOT opted into the new retry behavior
+      false, // ensure we are NOT opted into the new retry behavior
     );
 
     // make the call with neither retry option passed at call time
@@ -2563,7 +2563,7 @@ describe('REST streaming apiCall return StreamArrayParser', () => {
     const apiCall = createApiCallStreaming(
       spy,
       streaming.StreamType.SERVER_STREAMING,
-      true
+      true,
     );
     const s = apiCall({}, undefined);
     assert.strictEqual(s.readable, true);
@@ -2575,7 +2575,7 @@ describe('REST streaming apiCall return StreamArrayParser', () => {
     s.on('end', () => {
       assert.strictEqual(
         JSON.stringify(actualResults),
-        JSON.stringify([{resources: [1, 2]}, {resources: [3, 4, 5]}])
+        JSON.stringify([{resources: [1, 2]}, {resources: [3, 4, 5]}]),
       );
       done();
     });
@@ -2593,7 +2593,7 @@ describe('REST streaming apiCall return StreamArrayParser', () => {
     const apiCall = createApiCallStreaming(
       spy,
       streaming.StreamType.SERVER_STREAMING,
-      true
+      true,
     );
     const s = apiCall({}, undefined);
     assert.strictEqual(s.readable, true);
diff --git a/gax/test/unit/transcoding.ts b/gax/test/unit/transcoding.ts
index 1293ce2ef..f6c6669c6 100644
--- a/gax/test/unit/transcoding.ts
+++ b/gax/test/unit/transcoding.ts
@@ -32,7 +32,7 @@ import {
   buildQueryStringComponents,
   overrideHttpRules,
 } from '../../src/transcoding';
-import * as assert from 'assert';
+import assert from 'assert';
 import * as protobuf from 'protobufjs';
 import echoProtoJson = require('../fixtures/echo.json');
 import {google} from '../../protos/http';
@@ -85,7 +85,7 @@ describe('gRPC to HTTP transcoding', () => {
         url: '/v3/projects/project/supportedLanguages',
         queryString: '',
         data: '',
-      }
+      },
     );
 
     assert.deepStrictEqual(
@@ -95,46 +95,46 @@ describe('gRPC to HTTP transcoding', () => {
         url: '/v3/projects/project/supportedLanguages',
         queryString: 'field=value',
         data: '',
-      }
+      },
     );
 
     assert.deepStrictEqual(
       transcode(
         {parent: 'projects/project', field: 'value', a: 42},
-        parsedOptions
+        parsedOptions,
       ),
       {
         httpMethod: 'get',
         url: '/v3/projects/project/supportedLanguages',
         queryString: 'field=value&a=42',
         data: '',
-      }
+      },
     );
 
     assert.deepStrictEqual(
       transcode(
         {parent: 'post1/project', field: 'value', a: 42},
-        parsedOptions
+        parsedOptions,
       ),
       {
         httpMethod: 'post',
         url: '/v3/post1/project/supportedLanguages',
         queryString: '',
         data: {field: 'value', a: 42},
-      }
+      },
     );
 
     assert.deepStrictEqual(
       transcode(
         {parent: 'post2/project', field: 'value', a: 42},
-        parsedOptions
+        parsedOptions,
       ),
       {
         httpMethod: 'post',
         url: '/v3/post2/project/supportedLanguages',
         queryString: 'a=42',
         data: 'value',
-      }
+      },
     );
 
     assert.deepStrictEqual(
@@ -144,7 +144,7 @@ describe('gRPC to HTTP transcoding', () => {
         url: '/v3/get/project/value/supportedLanguages',
         queryString: 'a=42',
         data: '',
-      }
+      },
     );
 
     // Checking camel-snake-case conversions
@@ -155,14 +155,14 @@ describe('gRPC to HTTP transcoding', () => {
           snakeCaseBody: {snakeCaseField: 42},
           fieldName: 'value',
         },
-        parsedOptions
+        parsedOptions,
       ),
       {
         httpMethod: 'post',
         url: '/v3/a/first',
         queryString: 'fieldName=value',
         data: {snakeCaseField: 42},
-      }
+      },
     );
 
     assert.deepStrictEqual(
@@ -172,19 +172,19 @@ describe('gRPC to HTTP transcoding', () => {
           snakeCaseBody: {snakeCaseField: 42},
           fieldName: 'value',
         },
-        parsedOptions
+        parsedOptions,
       ),
       {
         httpMethod: 'post',
         url: '/v3/b/second',
         queryString: '',
         data: {snakeCaseBody: {snakeCaseField: 42}, fieldName: 'value'},
-      }
+      },
     );
 
     assert.strictEqual(
       transcode({unknownField: 'project'}, parsedOptions),
-      undefined
+      undefined,
     );
   });
 
@@ -217,7 +217,7 @@ describe('gRPC to HTTP transcoding', () => {
           parent: 'post1/project',
           IPProtocol: 'tcp',
         },
-        parsedOptions
+        parsedOptions,
       ),
       {
         httpMethod: 'post',
@@ -226,7 +226,7 @@ describe('gRPC to HTTP transcoding', () => {
         data: {
           IPProtocol: 'tcp',
         },
-      }
+      },
     );
     assert.deepStrictEqual(
       transcode(
@@ -235,14 +235,14 @@ describe('gRPC to HTTP transcoding', () => {
           IPProtocol: 'tcp',
           field: 'value',
         },
-        parsedOptions
+        parsedOptions,
       ),
       {
         httpMethod: 'post',
         queryString: 'IPProtocol=tcp',
         url: '/v3/post2/project/supportedLanguages',
         data: 'value',
-      }
+      },
     );
     assert.deepStrictEqual(
       transcode(
@@ -250,7 +250,7 @@ describe('gRPC to HTTP transcoding', () => {
           parent: 'post1/project',
           iPProtocol: 'tcp',
         },
-        parsedOptions
+        parsedOptions,
       ),
       {
         httpMethod: 'post',
@@ -259,7 +259,7 @@ describe('gRPC to HTTP transcoding', () => {
         data: {
           iPProtocol: 'tcp',
         },
-      }
+      },
     );
   });
 
@@ -290,38 +290,38 @@ describe('gRPC to HTTP transcoding', () => {
   it('getField', () => {
     assert.strictEqual(
       getField({field: 'stringValue'}, 'field'),
-      'stringValue'
+      'stringValue',
     );
     assert.strictEqual(
       getField({field: 'stringValue'}, 'nosuchfield'),
-      undefined
+      undefined,
     );
     assert.strictEqual(
       getField({field: 'stringValue'}, 'field.subfield'),
-      undefined
+      undefined,
     );
     assert.strictEqual(
       getField({field: {subfield: 'stringValue'}}, 'field.subfield'),
-      'stringValue'
+      'stringValue',
     );
     assert.deepStrictEqual(
       getField({field: {subfield: [1, 2, 3]}}, 'field.subfield'),
-      [1, 2, 3]
+      [1, 2, 3],
     );
     assert.strictEqual(
       getField({field: {subfield: 'stringValue'}}, 'field'),
-      undefined
+      undefined,
     );
     assert.strictEqual(
       getField({field: {subfield: 'stringValue'}}, 'field.nosuchfield'),
-      undefined
+      undefined,
     );
     assert.strictEqual(
       getField(
         {field: {subfield: {subsubfield: 'stringValue'}}},
-        'field.subfield.subsubfield'
+        'field.subfield.subsubfield',
       ),
-      'stringValue'
+      'stringValue',
     );
   });
 
@@ -364,9 +364,9 @@ describe('gRPC to HTTP transcoding', () => {
     assert.strictEqual(encodeWithSlashes('тест'), '%D1%82%D0%B5%D1%81%D1%82');
     assert.strictEqual(
       encodeWithSlashes(
-        '_.~0-9abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/ '
+        '_.~0-9abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/ ',
       ),
-      '_.~0-9abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ%2F%20'
+      '_.~0-9abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ%2F%20',
     );
   });
 
@@ -374,13 +374,13 @@ describe('gRPC to HTTP transcoding', () => {
     assert.strictEqual(encodeWithoutSlashes('abcd'), 'abcd');
     assert.strictEqual(
       encodeWithoutSlashes('тест'),
-      '%D1%82%D0%B5%D1%81%D1%82'
+      '%D1%82%D0%B5%D1%81%D1%82',
     );
     assert.strictEqual(
       encodeWithoutSlashes(
-        '_.~0-9abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/ '
+        '_.~0-9abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/ ',
       ),
-      '_.~0-9abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/%20'
+      '_.~0-9abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/%20',
     );
   });
 
@@ -390,24 +390,24 @@ describe('gRPC to HTTP transcoding', () => {
     assert.strictEqual(applyPattern('fail', 'test'), undefined);
     assert.strictEqual(
       applyPattern('projects/*', 'projects/test'),
-      'projects/test'
+      'projects/test',
     );
     assert.strictEqual(
       applyPattern('projects/*/locations/*', 'projects/test'),
-      undefined
+      undefined,
     );
     assert.strictEqual(applyPattern('locations/*', 'projects/test'), undefined);
     assert.strictEqual(
       applyPattern('projects/*/locations/*', 'projects/test/locations/us'),
-      'projects/test/locations/us'
+      'projects/test/locations/us',
     );
     assert.strictEqual(
       applyPattern('projects/*/locations/*', 'projects/test/locations/us/q/z'),
-      undefined
+      undefined,
     );
     assert.strictEqual(
       applyPattern('projects/*/locations/**', 'projects/test/locations/us/q/z'),
-      'projects/test/locations/us/q/z'
+      'projects/test/locations/us/q/z',
     );
   });
 
@@ -416,7 +416,7 @@ describe('gRPC to HTTP transcoding', () => {
     assert.deepStrictEqual(flattenObject({field: 'value'}), {field: 'value'});
     assert.deepStrictEqual(
       flattenObject({field: 'value', nested: {subfield: 'subvalue'}}),
-      {field: 'value', 'nested.subfield': 'subvalue'}
+      {field: 'value', 'nested.subfield': 'subvalue'},
     );
   });
 
@@ -424,46 +424,46 @@ describe('gRPC to HTTP transcoding', () => {
     assert.deepStrictEqual(
       match(
         {parent: 'projects/te st', test: 'value'},
-        '/v3/{parent=projects/*}/supportedLanguages'
+        '/v3/{parent=projects/*}/supportedLanguages',
       ),
       {
         matchedFields: ['parent'],
         url: '/v3/projects/te%20st/supportedLanguages',
-      }
+      },
     );
     assert.deepStrictEqual(
       match(
         {parent: 'projects/te st/locations/location', test: 'value'},
-        '/v3/{parent=projects/*}/supportedLanguages'
+        '/v3/{parent=projects/*}/supportedLanguages',
       ),
-      undefined
+      undefined,
     );
     assert.deepStrictEqual(
       match(
         {parent: 'projects/te st/locations/location', test: 'value'},
-        '/v3/{parent=projects/*/locations/*}/supportedLanguages'
+        '/v3/{parent=projects/*/locations/*}/supportedLanguages',
       ),
       {
         matchedFields: ['parent'],
         url: '/v3/projects/te%20st/locations/location/supportedLanguages',
-      }
+      },
     );
     assert.deepStrictEqual(
       match(
         {parent: 'projects/te st', test: 'value'},
-        '/v3/{parent=projects/*}/{field=*}/supportedLanguages'
+        '/v3/{parent=projects/*}/{field=*}/supportedLanguages',
       ),
-      undefined
+      undefined,
     );
     assert.deepStrictEqual(
       match(
         {parent: 'projects/te st', test: 'value', field: 42},
-        '/v3/{parent=projects/*}/{field=*}/supportedLanguages'
+        '/v3/{parent=projects/*}/{field=*}/supportedLanguages',
       ),
       {
         matchedFields: ['field', 'parent'],
         url: '/v3/projects/te%20st/42/supportedLanguages',
-      }
+      },
     );
     assert.deepStrictEqual(
       match(
@@ -473,23 +473,23 @@ describe('gRPC to HTTP transcoding', () => {
           field: 'fields/field42',
           path: 'a/b,c/d',
         },
-        '/v3/{parent=projects/*}/{field=fields/*}/{path=**}/supportedLanguages'
+        '/v3/{parent=projects/*}/{field=fields/*}/{path=**}/supportedLanguages',
       ),
       {
         matchedFields: ['path', 'field', 'parent'],
         url: '/v3/projects/te%20st/fields/field42/a/b%2Cc/d/supportedLanguages',
-      }
+      },
     );
     assert.deepStrictEqual(
       match({}, '/v3/{field.subfield}/supportedLanguages'),
-      undefined
+      undefined,
     );
     assert.deepStrictEqual(
       match({field: {subfield: 42}}, '/v3/{field.subfield}/supportedLanguages'),
       {
         matchedFields: ['field.subfield'],
         url: '/v3/42/supportedLanguages',
-      }
+      },
     );
   });
 
@@ -503,7 +503,7 @@ describe('gRPC to HTTP transcoding', () => {
     };
     const copy = deepCopyWithoutMatchedFields(
       request as RequestType,
-      new Set()
+      new Set(),
     );
     assert.deepStrictEqual(copy, request);
     request.field.subfield = 43;
@@ -532,7 +532,7 @@ describe('gRPC to HTTP transcoding', () => {
     };
     const copy = deepCopyWithoutMatchedFields(
       request as RequestType,
-      new Set(['field.subfield'])
+      new Set(['field.subfield']),
     );
     assert.deepStrictEqual(copy, expected);
   });
@@ -543,7 +543,7 @@ describe('gRPC to HTTP transcoding', () => {
     ]);
     assert.deepStrictEqual(
       buildQueryStringComponents({field: 'value', a: 42}),
-      ['field=value', 'a=42']
+      ['field=value', 'a=42'],
     );
     assert.deepStrictEqual(
       buildQueryStringComponents({
@@ -558,7 +558,7 @@ describe('gRPC to HTTP transcoding', () => {
         'repeated=z%20z%20z',
         'obj.subfield=string',
         'obj.y=z',
-      ]
+      ],
     );
   });
 });
@@ -615,7 +615,7 @@ describe('override the HTTP rules in protoJson', () => {
         assert.deepStrictEqual(httpOptions.get, rule.get);
         assert.deepStrictEqual(
           httpOptions.additional_bindings,
-          rule.additional_bindings
+          rule.additional_bindings,
         );
       }
     }
@@ -645,7 +645,7 @@ describe('override the HTTP rules in protoJson', () => {
     };
     assert(originAdditionalBindings());
     const expectedAditionalBindings = originAdditionalBindings()!.concat(
-      httpRules[0].additional_bindings
+      httpRules[0].additional_bindings,
     );
     overrideHttpRules(httpRules, root);
     for (const rule of httpRules) {
@@ -660,7 +660,7 @@ describe('override the HTTP rules in protoJson', () => {
         assert.deepStrictEqual(httpOptions.get, rule.get);
         assert.deepStrictEqual(
           httpOptions.additional_bindings,
-          expectedAditionalBindings
+          expectedAditionalBindings,
         );
       }
     }
diff --git a/gax/test/unit/util.ts b/gax/test/unit/util.ts
index 614e1c06f..e9e882a36 100644
--- a/gax/test/unit/util.ts
+++ b/gax/test/unit/util.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import {describe, it} from 'mocha';
 import {
   toCamelCase as snakeToCamelCase,
@@ -37,7 +37,7 @@ describe('util.ts', () => {
     assert.strictEqual(camelToSnakeCase('a.1B'), 'a.1_b');
     assert.strictEqual(
       camelToSnakeCase('somethingABCDEValue`'),
-      'something_a_b_c_d_e_value'
+      'something_a_b_c_d_e_value',
     );
   });
 
@@ -53,7 +53,7 @@ describe('util.ts', () => {
     assert.strictEqual(snakeToCamelCase('a.1_b'), 'a.1B');
     assert.strictEqual(
       snakeToCamelCase('something_abcde_value'),
-      'somethingAbcdeValue'
+      'somethingAbcdeValue',
     );
   });
 
@@ -69,15 +69,15 @@ describe('util.ts', () => {
     assert.strictEqual(toLowerCamelCase('a.1_b'), 'a.1B');
     assert.strictEqual(
       toLowerCamelCase('something_abcde_value'),
-      'somethingAbcdeValue'
+      'somethingAbcdeValue',
     );
     assert.strictEqual(
       toLowerCamelCase('PascalCaseString'),
-      'pascalCaseString'
+      'pascalCaseString',
     );
     assert.strictEqual(
       toLowerCamelCase('PascalCASEString'),
-      'pascalCaseString'
+      'pascalCaseString',
     );
   });
 
diff --git a/gax/test/unit/utils.ts b/gax/test/unit/utils.ts
index 24f53d89f..664ec45f9 100644
--- a/gax/test/unit/utils.ts
+++ b/gax/test/unit/utils.ts
@@ -28,7 +28,7 @@ export function fail(
   argument: {},
   metadata: {},
   options: Options,
-  callback: Function
+  callback: Function,
 ) {
   const error = new GoogleError();
   error.code = FAKE_STATUS_CODE_1;
@@ -76,7 +76,7 @@ export function createApiCall(func: Function, opts?: Options) {
       };
     }),
     settings,
-    descriptor
+    descriptor,
   ) as GaxCallPromise;
 }
 
@@ -87,7 +87,7 @@ export function createRetryOptions(
   initialRpcTimeoutMillis?: number,
   rpcTimeoutMultiplier?: number,
   maxRpcTimeoutMillis?: number,
-  totalTimeoutMillis?: number
+  totalTimeoutMillis?: number,
 ) {
   const backoff =
     typeof backoffSettingsOrInitialRetryDelayMillis === 'number'
@@ -98,7 +98,7 @@ export function createRetryOptions(
           initialRpcTimeoutMillis!,
           rpcTimeoutMultiplier!,
           maxRpcTimeoutMillis!,
-          totalTimeoutMillis!
+          totalTimeoutMillis!,
         )
       : backoffSettingsOrInitialRetryDelayMillis;
   return gax.createRetryOptions([FAKE_STATUS_CODE_1], backoff);
@@ -108,7 +108,7 @@ export function toProtobufJSON(protobufType: protobuf.Type, json: {}) {
   const message = serializer.fromProto3JSON(protobufType, json);
   if (!message) {
     throw new Error(
-      `Internal Error: fail to convert JSON to protobuf specific JSON, protobuf type: ${protobufType}`
+      `Internal Error: fail to convert JSON to protobuf specific JSON, protobuf type: ${protobufType}`,
     );
   }
   return protobufType.toObject(message, defaultToObjectOptions);
diff --git a/gax/test/unit/warning.ts b/gax/test/unit/warning.ts
index 8453e8105..240523321 100644
--- a/gax/test/unit/warning.ts
+++ b/gax/test/unit/warning.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import * as assert from 'assert';
+import assert from 'assert';
 import * as sinon from 'sinon';
 import {describe, it} from 'mocha';
 
@@ -48,7 +48,7 @@ describe('warnings', () => {
     assert(
       stub.calledWith('messageD-1', {
         type: 'WarningType1',
-      })
+      }),
     );
     stub.restore();
     done();
diff --git a/gax/tsconfig.json b/gax/tsconfig.json
index 0921b23c8..d5cda5d87 100644
--- a/gax/tsconfig.json
+++ b/gax/tsconfig.json
@@ -5,7 +5,11 @@
     "rootDir": ".",
     "outDir": "build",
     "noImplicitAny": true,
-    "resolveJsonModule": true
+    "resolveJsonModule": true,
+    "moduleResolution": "node16",
+    "esModuleInterop": true,
+    "module": "node16",
+    "skipLibCheck": true
   },
   "include": [
     "src/*.ts",
@@ -15,5 +19,8 @@
     "src/*/*.ts",
     "test/system-test/*.ts",
     "test/unit/*.ts",
+    "protos/**/*.json",
+    "src/*.json",
+    "test/fixtures/*.json"
   ]
 }
diff --git a/gax/webpack.config.js b/gax/webpack.config.js
index 03705217e..83bf18ce5 100644
--- a/gax/webpack.config.js
+++ b/gax/webpack.config.js
@@ -28,12 +28,12 @@ module.exports = {
       '../../package.json': path.resolve(__dirname, 'package.json'),
       '../../protos/operations.json': path.resolve(
         __dirname,
-        'protos/operations.json'
+        'protos/operations.json',
       ),
       '../../protos/status.json': path.resolve(__dirname, 'protos/status.json'),
       '../../protos/iam_service.json': path.resolve(
         __dirname,
-        'protos/iam_service.json'
+        'protos/iam_service.json',
       ),
     },
   },
diff --git a/package-lock.json b/package-lock.json
index e12807202..dcbf3b673 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -7,7 +7,7 @@
       "name": "gax-nodejs",
       "license": "Apache-2.0",
       "engines": {
-        "node": ">=14"
+        "node": ">=18"
       }
     }
   }
diff --git a/package.json b/package.json
index e0003f91f..4717726b2 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,7 @@
     "url": "https://github.com/googleapis/gax-nodejs/issues"
   },
   "engines": {
-    "node": ">=14"
+    "node": ">=18"
   },
   "homepage": "https://github.com/googleapis/gax-nodejs#readme"
 }
diff --git a/tools/package.json b/tools/package.json
index 2e175337e..ebc784307 100644
--- a/tools/package.json
+++ b/tools/package.json
@@ -28,14 +28,14 @@
   "author": "Google API Authors",
   "license": "Apache-2.0",
   "dependencies": {
-    "@babel/core": "^7.22.5",
-    "@babel/traverse": "^7.22.5",
-    "google-gax": "^4.3.2",
+    "@babel/core": "^7.26.8",
+    "@babel/traverse": "^7.26.8",
+    "google-gax": "^4.4.1",
     "google-proto-files": "^4.2.0",
-    "protobufjs-cli": "1.1.3",
-    "uglify-js": "^3.17.0",
-    "walk-up-path": "^3.0.1",
-    "walkdir": "^0.4.0"
+    "protobufjs-cli": "^1.1.3",
+    "uglify-js": "^3.19.3",
+    "walk-up-path": "^3.0.0",
+    "walkdir": "^0.4.1"
   },
   "repository": {
     "type": "git",
@@ -43,21 +43,21 @@
     "directory": "gapic-tools"
   },
   "devDependencies": {
-    "@babel/cli": "^7.22.5",
-    "@babel/types": "^7.22.5",
-    "@types/babel__core": "^7.20.1",
-    "@types/babel__traverse": "^7.20.1",
-    "@types/mocha": "^9.0.0",
-    "@types/ncp": "^2.0.1",
-    "@types/uglify-js": "^3.17.0",
-    "c8": "^9.0.0",
-    "gts": "^5.0.0",
-    "mocha": "^9.0.0",
+    "@babel/cli": "^7.26.4",
+    "@babel/types": "^7.26.8",
+    "@types/babel__core": "^7.20.5",
+    "@types/babel__traverse": "^7.20.6",
+    "@types/mocha": "^10.0.10",
+    "@types/ncp": "^2.0.8",
+    "@types/uglify-js": "^3.17.5",
+    "c8": "^10.1.3",
+    "gts": "^6.0.2",
+    "mocha": "^11.1.0",
     "ncp": "^2.0.0",
-    "protobufjs": "7.4.0",
-    "typescript": "^5.1.6"
+    "protobufjs": "^7.4.0",
+    "typescript": "^5.7.3"
   },
   "engines": {
-    "node": ">=14"
+    "node": ">=18"
   }
 }
diff --git a/tools/src/compileProtos.ts b/tools/src/compileProtos.ts
index 81c9981be..06e92890f 100644
--- a/tools/src/compileProtos.ts
+++ b/tools/src/compileProtos.ts
@@ -28,7 +28,7 @@ export const gaxProtos = path.join(
   require.resolve('google-gax'),
   '..',
   '..',
-  'protos'
+  'protos',
 );
 const readdir = util.promisify(fs.readdir);
 const readFile = util.promisify(fs.readFile);
@@ -95,7 +95,7 @@ function getAllEnums(dts: string): Set<string> {
   let currentEnum = undefined;
   for (const line of lines) {
     const match = line.match(
-      /^\s*(?:export )?(namespace|class|interface|enum) (\w+) .*{/
+      /^\s*(?:export )?(namespace|class|interface|enum) (\w+) .*{/,
     );
     if (match) {
       const [, keyword, id] = match;
@@ -144,7 +144,7 @@ function updateDtsTypes(dts: string, enums: Set<string>): string {
       // enum: E => E|keyof typeof E  to allow all string values
       replaced = replaced.replace(
         typeName,
-        `${typeName}|keyof typeof ${typeName}`
+        `${typeName}|keyof typeof ${typeName}`,
       );
     } else if (typeName === 'Uint8Array') {
       // bytes: Uint8Array => Uint8Array|Buffer|string to allow base64-encoded strings
@@ -170,14 +170,14 @@ function fixJsFile(js: string): string {
   // depend on protobufjs, so we re-export it from google-gax
   js = js.replace(
     'import * as $protobuf from "protobufjs/minimal"',
-    'import {protobufMinimal  as $protobuf} from "google-gax/build/src/protobuf.js"'
+    'import {protobufMinimal  as $protobuf} from "google-gax/build/src/protobuf.js"',
   );
 
   // 1. fix protobufjs require: we don't want the libraries to
   // depend on protobufjs, so we re-export it from google-gax
   js = js.replace(
     'require("protobufjs/minimal")',
-    'require("google-gax/build/src/protobuf").protobufMinimal'
+    'require("google-gax/build/src/protobuf").protobufMinimal',
   );
 
   // 2. add Apache license to the generated .js file
@@ -192,7 +192,7 @@ function fixDtsFile(dts: string): string {
   // 1. fix for pbts output to make sure we import Long properly
   dts = dts.replace(
     'import * as Long from "long";',
-    'import Long = require("long");'
+    'import Long = require("long");',
   );
   if (!dts.match(/import Long = require/)) {
     dts = 'import Long = require("long");\n' + dts;
@@ -202,7 +202,7 @@ function fixDtsFile(dts: string): string {
   // depend on protobufjs, so we re-export it from google-gax
   dts = dts.replace(
     'import * as $protobuf from "protobufjs"',
-    'import type {protobuf as $protobuf} from "google-gax"'
+    'import type {protobuf as $protobuf} from "google-gax"',
   );
 
   // 3. add Apache license to the generated .d.ts file
@@ -223,7 +223,7 @@ function fixDtsFile(dts: string): string {
  */
 async function buildListOfProtos(
   protoJsonFiles: string[],
-  esm?: boolean
+  esm?: boolean,
 ): Promise<string[]> {
   const result: string[] = [];
   for (const file of protoJsonFiles) {
@@ -233,7 +233,7 @@ async function buildListOfProtos(
       // If we're in ESM, we're going to be in a directory level below normal
       esm
         ? path.join(directory, '..', normalizePath(filePath))
-        : path.join(directory, normalizePath(filePath))
+        : path.join(directory, normalizePath(filePath)),
     );
     result.push(...list);
   }
@@ -259,7 +259,7 @@ interface CompileProtosOptions {
 async function compileProtos(
   rootName: string,
   protos: string[],
-  options: CompileProtosOptions
+  options: CompileProtosOptions,
 ): Promise<void> {
   const extraArgs = [];
   if (options.keepCase) {
@@ -439,16 +439,16 @@ export async function main(parameters: string[]): Promise<void> {
  */
 function usage() {
   console.log(
-    `Usage: node ${process.argv[1]} [--skip-json] [--esm] directory ...`
+    `Usage: node ${process.argv[1]} [--skip-json] [--esm] directory ...`,
   );
   console.log(
-    `Finds all files matching ${PROTO_LIST_REGEX} in the given directories.`
+    `Finds all files matching ${PROTO_LIST_REGEX} in the given directories.`,
   );
   console.log(
-    'Each of those files should contain a JSON array of proto files used by the'
+    'Each of those files should contain a JSON array of proto files used by the',
   );
   console.log(
-    'client library. Those proto files will be compiled to JSON using pbjs tool'
+    'client library. Those proto files will be compiled to JSON using pbjs tool',
   );
   console.log('from protobufjs.');
 }
@@ -460,5 +460,6 @@ if (require.main === module) {
     process.exit(1);
   }
   // argv[0] is node.js binary, argv[1] is script path
+  // eslint-disable-next-line @typescript-eslint/no-floating-promises
   main(process.argv.slice(2));
 }
diff --git a/tools/src/listProtos.ts b/tools/src/listProtos.ts
index ae797919f..85d79fd8b 100644
--- a/tools/src/listProtos.ts
+++ b/tools/src/listProtos.ts
@@ -32,7 +32,7 @@ async function main(directory: string) {
 
   fs.writeFileSync(
     outputFile,
-    JSON.stringify(commonProtoFiles, null, 2) + '\n'
+    JSON.stringify(commonProtoFiles, null, 2) + '\n',
   );
 }
 /**
@@ -46,5 +46,6 @@ if (require.main === module) {
   if (process.argv.length < 3 || process.argv[2] === '--help') {
     usage();
   }
+  // eslint-disable-next-line @typescript-eslint/no-floating-promises
   main(process.argv[2]);
 }
diff --git a/tools/src/minify.ts b/tools/src/minify.ts
index d12931314..08c71f51c 100644
--- a/tools/src/minify.ts
+++ b/tools/src/minify.ts
@@ -60,10 +60,10 @@ export async function main(directory?: string) {
 function usage() {
   console.log(`Usage: node ${process.argv[1]} [directory]`);
   console.log(
-    'Minifies all JSON files in-place in the given directory (non-recursively).'
+    'Minifies all JSON files in-place in the given directory (non-recursively).',
   );
   console.log(
-    'If no directory is given, minifies JSON files in ./build/protos.'
+    'If no directory is given, minifies JSON files in ./build/protos.',
   );
 }
 
@@ -76,5 +76,6 @@ if (require.main === module) {
     process.exit(1);
   }
 
+  // eslint-disable-next-line @typescript-eslint/no-floating-promises
   main(process.argv[2]);
 }
diff --git a/tools/src/prepublish.ts b/tools/src/prepublish.ts
index 371a9b77e..4f1d750c8 100755
--- a/tools/src/prepublish.ts
+++ b/tools/src/prepublish.ts
@@ -70,6 +70,6 @@ if (require.main === module) {
     // eslint-disable-next-line n/no-process-exit
     process.exit(1);
   }
-
+  // eslint-disable-next-line @typescript-eslint/no-floating-promises
   main(process.argv[2]);
 }
diff --git a/tools/test/compileProtos.ts b/tools/test/compileProtos.ts
index e5704e8c7..a30ccdcd5 100644
--- a/tools/test/compileProtos.ts
+++ b/tools/test/compileProtos.ts
@@ -93,12 +93,12 @@ describe('compileProtos tool', () => {
     assert(js.toString().includes('TestMessage'));
     assert(js.toString().includes('LibraryService'));
     assert(
-      js.toString().includes('http://www.apache.org/licenses/LICENSE-2.0')
+      js.toString().includes('http://www.apache.org/licenses/LICENSE-2.0'),
     );
     assert(
       js
         .toString()
-        .includes('require("google-gax/build/src/protobuf").protobufMinimal')
+        .includes('require("google-gax/build/src/protobuf").protobufMinimal'),
     );
     assert(!js.toString().includes('require("protobufjs/minimal")'));
 
@@ -111,12 +111,12 @@ describe('compileProtos tool', () => {
     assert(ts.toString().includes('import Long = require'));
     assert(!ts.toString().includes('import * as Long'));
     assert(
-      ts.toString().includes('http://www.apache.org/licenses/LICENSE-2.0')
+      ts.toString().includes('http://www.apache.org/licenses/LICENSE-2.0'),
     );
     assert(
       ts
         .toString()
-        .includes('import type {protobuf as $protobuf} from "google-gax"')
+        .includes('import type {protobuf as $protobuf} from "google-gax"'),
     );
     assert(!ts.toString().includes('import * as $protobuf from "protobufjs"'));
   });
@@ -138,12 +138,12 @@ describe('compileProtos tool', () => {
     assert(cjs.toString().includes('TestMessage'));
     assert(cjs.toString().includes('LibraryService'));
     assert(
-      cjs.toString().includes('http://www.apache.org/licenses/LICENSE-2.0')
+      cjs.toString().includes('http://www.apache.org/licenses/LICENSE-2.0'),
     );
     assert(
       cjs
         .toString()
-        .includes('require("google-gax/build/src/protobuf").protobufMinimal')
+        .includes('require("google-gax/build/src/protobuf").protobufMinimal'),
     );
     assert(!cjs.toString().includes('require("protobufjs/minimal")'));
 
@@ -154,18 +154,20 @@ describe('compileProtos tool', () => {
     assert(js.toString().includes('TestMessage'));
     assert(js.toString().includes('LibraryService'));
     assert(
-      js.toString().includes('http://www.apache.org/licenses/LICENSE-2.0')
+      js.toString().includes('http://www.apache.org/licenses/LICENSE-2.0'),
     );
     assert(
       js
         .toString()
         .includes(
-          'import {protobufMinimal  as $protobuf} from "google-gax/build/src/protobuf.js"'
-        )
+          'import {protobufMinimal  as $protobuf} from "google-gax/build/src/protobuf.js"',
+        ),
     );
     assert(!js.toString().includes('require("protobufjs/minimal")'));
     assert(
-      !js.toString().includes('import * as $protobuf from "protobufjs/minimal"')
+      !js
+        .toString()
+        .includes('import * as $protobuf from "protobufjs/minimal"'),
     );
 
     // check that it uses proper root object; it's taken from fixtures/package.json
@@ -177,12 +179,12 @@ describe('compileProtos tool', () => {
     assert(ts.toString().includes('import Long = require'));
     assert(!ts.toString().includes('import * as Long'));
     assert(
-      ts.toString().includes('http://www.apache.org/licenses/LICENSE-2.0')
+      ts.toString().includes('http://www.apache.org/licenses/LICENSE-2.0'),
     );
     assert(
       ts
         .toString()
-        .includes('import type {protobuf as $protobuf} from "google-gax"')
+        .includes('import type {protobuf as $protobuf} from "google-gax"'),
     );
     assert(!ts.toString().includes('import * as $protobuf from "protobufjs"'));
   });
@@ -198,12 +200,12 @@ describe('compileProtos tool', () => {
     assert(js.toString().includes('TestMessage'));
     assert(js.toString().includes('LibraryService'));
     assert(
-      js.toString().includes('http://www.apache.org/licenses/LICENSE-2.0')
+      js.toString().includes('http://www.apache.org/licenses/LICENSE-2.0'),
     );
     assert(
       js
         .toString()
-        .includes('require("google-gax/build/src/protobuf").protobufMinimal')
+        .includes('require("google-gax/build/src/protobuf").protobufMinimal'),
     );
     assert(!js.toString().includes('require("protobufjs/minimal")'));
 
@@ -216,12 +218,12 @@ describe('compileProtos tool', () => {
     assert(ts.toString().includes('import Long = require'));
     assert(!ts.toString().includes('import * as Long'));
     assert(
-      ts.toString().includes('http://www.apache.org/licenses/LICENSE-2.0')
+      ts.toString().includes('http://www.apache.org/licenses/LICENSE-2.0'),
     );
     assert(
       ts
         .toString()
-        .includes('import type {protobuf as $protobuf} from "google-gax"')
+        .includes('import type {protobuf as $protobuf} from "google-gax"'),
     );
     assert(!ts.toString().includes('import * as $protobuf from "protobufjs"'));
   });
@@ -239,43 +241,43 @@ describe('compileProtos tool', () => {
     assert(ts.toString().includes('import Long = require'));
     assert(!ts.toString().includes('import * as Long'));
     assert(
-      ts.toString().includes('http://www.apache.org/licenses/LICENSE-2.0')
+      ts.toString().includes('http://www.apache.org/licenses/LICENSE-2.0'),
     );
     assert(ts.toString().includes('longField?: (number|Long|string|null);'));
     assert(
-      ts.toString().includes('bytesField?: (Uint8Array|Buffer|string|null);')
+      ts.toString().includes('bytesField?: (Uint8Array|Buffer|string|null);'),
     );
     assert(
       ts
         .toString()
         .includes(
-          'enumField?: (google.TestEnum|keyof typeof google.TestEnum|null);'
-        )
+          'enumField?: (google.TestEnum|keyof typeof google.TestEnum|null);',
+        ),
     );
     assert(
       ts
         .toString()
         .includes(
-          '"case"?: (google.TestEnum|keyof typeof google.TestEnum|null);'
-        )
+          '"case"?: (google.TestEnum|keyof typeof google.TestEnum|null);',
+        ),
     );
     assert(ts.toString().includes('public longField: (number|Long|string);'));
     assert(
-      ts.toString().includes('public bytesField: (Uint8Array|Buffer|string);')
+      ts.toString().includes('public bytesField: (Uint8Array|Buffer|string);'),
     );
     assert(
       ts
         .toString()
         .includes(
-          'public enumField: (google.TestEnum|keyof typeof google.TestEnum);'
-        )
+          'public enumField: (google.TestEnum|keyof typeof google.TestEnum);',
+        ),
     );
     assert(
       ts
         .toString()
         .includes(
-          'public case: (google.TestEnum|keyof typeof google.TestEnum);'
-        )
+          'public case: (google.TestEnum|keyof typeof google.TestEnum);',
+        ),
     );
   });
 
diff --git a/tools/test/replaceESMMockingLib.ts b/tools/test/replaceESMMockingLib.ts
index 51aa7d565..cd41a46ec 100644
--- a/tools/test/replaceESMMockingLib.ts
+++ b/tools/test/replaceESMMockingLib.ts
@@ -101,7 +101,7 @@ describe('replace ESM mocking lib', () => {
 
       assert.strictEqual(
         result?.code?.replace(/(\r\n|\n|\r)/gm, '').replace('  ', ''),
-        expected
+        expected,
       );
     });