truncate message and add tests

Author: Jack-Keene

plugins/browser-plugin-error-tracking/src/index.ts

@@ -36,7 +36,7 @@ import {
   dispatchToTrackersInCollection,
 } from '@snowplow/browser-tracker-core';
 import { buildSelfDescribingEvent, CommonEventProperties, SelfDescribingJson } from '@snowplow/tracker-core';
-import { truncateStackTrace } from './util';
+import { truncateString } from './util';
 
 let _trackers: Record<string, BrowserTracker> = {};
 
@@ -75,7 +75,8 @@ export function trackError(
   trackers: Array<string> = Object.keys(_trackers)
 ) {
   const { message, filename, lineno, colno, error, context, timestamp } = event,
-    stack = error && truncateStackTrace(error.stack);
+    stack = error && truncateString(error.stack, 8192),
+    truncatedMessage = message && truncateString(message, 2048);
 
   dispatchToTrackersInCollection(trackers, _trackers, (t) => {
     t.core.track(
@@ -84,7 +85,7 @@ export function trackError(
           schema: 'iglu:com.snowplowanalytics.snowplow/application_error/jsonschema/1-0-1',
           data: {
             programmingLanguage: 'JAVASCRIPT',
-            message: message ?? "JS Exception. Browser doesn't support ErrorEvent API",
+            message: truncatedMessage ?? "JS Exception. Browser doesn't support ErrorEvent API",
             stackTrace: stack,
             lineNumber: lineno,
             lineColumn: colno,

plugins/browser-plugin-error-tracking/src/util.ts

@@ -1,21 +1,15 @@
 /**
- * Truncate stack trace if it's size is greater than 8kb
+ * Truncate string if it's longer than 8192 chars
  *
- * @param stackTrace - The stack trace to truncate
- * @returns The trucated stack trace
+ * @param string - The stack trace to truncate
+ * @param maxLength - The maximum length of the truncated string. Default = 8192
+ * @returns The truncated string
  */
-export function truncateStackTrace(stackTrace?: string): string | undefined {
-  const byteSize = (str: string) => new Blob([str]).size;
-
-  if (stackTrace && byteSize(stackTrace) > 8000) {
-    const encoder = new TextEncoder();
-    const encodedText = encoder.encode(stackTrace);
-    const truncatedEncodedText = encodedText.slice(0, 8000);
-    const decoder = new TextDecoder();
-    const truncatedStackTrace = decoder.decode(truncatedEncodedText);
-
-    return truncatedStackTrace;
+export function truncateString(string?: string, maxLength: number = 8192): string | undefined {
+  if (string && string.length > 8192) {
+    const truncatedString = string.substring(0, maxLength);
+    return truncatedString;
   }
 
-  return stackTrace;
+  return string;
 }

plugins/browser-plugin-error-tracking/test/events.test.ts

@@ -60,10 +60,18 @@ describe('AdTrackingPlugin', () => {
     encodeBase64: false,
     plugins: [ErrorTrackingPlugin()],
   });
+  addTracker('sp4', 'sp4', 'js-3.0.0', '', state, {
+    encodeBase64: false,
+    plugins: [ErrorTrackingPlugin()],
+  });
 
   const error = new Error('this is an error');
   error.stack = 'stacktrace-1';
 
+  const oversizedError = new Error('this is a longer error');
+  oversizedError.stack = 'x'.repeat(10000);
+  const oversizedMessage = 'y'.repeat(10000);
+
   trackError(
     {
       message: 'message-1',
@@ -89,6 +97,14 @@ describe('AdTrackingPlugin', () => {
     ['sp3']
   );
 
+  trackError(
+    {
+      message: oversizedMessage,
+      error: oversizedError,
+    },
+    ['sp4']
+  );
+
   it('trackError adds the expected application error event to the queue', () => {
     expect(
       extractUeEvent('iglu:com.snowplowanalytics.snowplow/application_error/jsonschema/1-0-1').from(state.outQueues[0])
@@ -126,4 +142,16 @@ describe('AdTrackingPlugin', () => {
       },
     });
   });
+
+  it('trackError replaces undefined messages with placeholder', () => {
+    expect(
+      extractUeEvent('iglu:com.snowplowanalytics.snowplow/application_error/jsonschema/1-0-1').from(state.outQueues[3])
+    ).toMatchObject({
+      schema: 'iglu:com.snowplowanalytics.snowplow/application_error/jsonschema/1-0-1',
+      data: {
+        message: 'y'.repeat(2048),
+        stackTrace: 'x'.repeat(8192),
+      },
+    });
+  });
 });