Do no move node_modules when generating NPM lockfile (#85)

Author: 0x80

README.md

@@ -68,9 +68,8 @@ integrated, check out [mono-ts](https://github.com/0x80/mono-ts)
 
 Run `pnpm install isolate-package --dev` or the equivalent for `npm` or `yarn`.
 
-It is recommended to use `pnpm` over `npm` or `yarn`. Apart from being fast and
-efficient, PNPM has better support for monorepos, and the lockfile isolation is
-solid and works in parallel for multiple packages, [unlike NPM](#npm)
+I recommended using `pnpm` over `npm` or `yarn`. Besides being fast and
+efficient, PNPM has better support for monorepos.
 
 ## Usage
 
@@ -331,17 +330,8 @@ each package manager, with NPM currently being the least attractive.
 ### NPM
 
 For NPM we use a tool called Arborist, which is an integral part of the NPM
-codebase. It is executed in the isolate output directory and requires the
-adapted lockfile and the `node_modules` directory from the root of the
-repository. As this directory is typically quite large, copying it over as part
-of the isolate flow is not very desirable.
-
-To work around this, we move it to the isolate output and then move it back
-after Arborist has finished doing its thing.
-
-> !! Warning: This will not be compatible with setups that run multiple
-> isolation processes in parallel. Hopefully a future update to NPM Arborist
-> (the part the generates the lockfile) will solve this.
+codebase. It is executed in the isolate output directory with an adaptation
+adapted manifest file.
 
 ### PNPM
 
@@ -355,11 +345,7 @@ dependencies of internally linked packages are not installed by PNPM.
 ### Classic Yarn
 
 For Yarn v1 we can simply copy the root lockfile to the isolate output, and run
-a `yarn install` to prune that lockfile. The command finds the installed node
-modules in the root of the monorepo so versions are preserved.
-
-> Note: I expect this to break down if you configure the isolate output
-> directory to be located outside the monorepo tree.
+a `yarn install` to prune that lockfile.
 
 ### Modern Yarn
 

src/lib/lockfile/helpers/generate-npm-lockfile.ts

@@ -2,7 +2,7 @@ import Arborist from "@npmcli/arborist";
 import fs from "fs-extra";
 import path from "node:path";
 import { useLogger } from "~/lib/logger";
-import { getErrorMessage, inspectValue } from "~/lib/utils";
+import { getErrorMessage } from "~/lib/utils";
 
 /**
  * Generate an isolated / pruned lockfile, based on the contents of installed
@@ -20,28 +20,15 @@ export async function generateNpmLockfile({
 
   log.debug("Generating NPM lockfile...");
 
-  const origRootNodeModulesPath = path.join(workspaceRootDir, "node_modules");
-  const tempRootNodeModulesPath = path.join(isolateDir, "node_modules");
-
-  let hasMovedNodeModules = false;
-
-  let hasError = false;
+  const nodeModulesPath = path.join(workspaceRootDir, "node_modules");
 
   try {
-    if (!fs.existsSync(origRootNodeModulesPath)) {
-      throw new Error(
-        `Failed to find node_modules at ${origRootNodeModulesPath}`
-      );
+    if (!fs.existsSync(nodeModulesPath)) {
+      throw new Error(`Failed to find node_modules at ${nodeModulesPath}`);
     }
 
-    log.debug(`Temporarily moving node_modules to the isolate output`);
-
-    await fs.move(origRootNodeModulesPath, tempRootNodeModulesPath);
-    hasMovedNodeModules = true;
-
     const arborist = new Arborist({ path: isolateDir });
 
-    log.debug(`Building tree...`);
     const { meta } = await arborist.buildIdealTree();
 
     meta?.commit();
@@ -52,18 +39,6 @@ export async function generateNpmLockfile({
 
     log.debug("Created lockfile at", lockfilePath);
   } catch (err) {
-    console.error(inspectValue(err));
-    log.error(`Failed to generate lockfile: ${getErrorMessage(err)}`);
-    hasError = true;
-  } finally {
-    /** @todo We should be able to use the new "using" keyword for this I think. */
-    if (hasMovedNodeModules) {
-      log.debug(`Restoring node_modules to the workspace root`);
-      await fs.move(tempRootNodeModulesPath, origRootNodeModulesPath);
-    }
-  }
-
-  if (hasError) {
-    throw new Error("Failed to generate lockfile");
+    throw new Error(`Failed to generate lockfile: ${getErrorMessage(err)}`);
   }
 }