Do not anonymize #note and #diff anchors in URLs

app/assets/javascripts/tracking/tracking.js

@@ -10,6 +10,8 @@ import {
   addReferrersCacheEntry,
 } from './utils';
 
+const ALLOWED_URL_HASHES = ['#diff', '#note'];
+
 export default class Tracking {
   static queuedEvents = [];
   static initialized = false;
@@ -183,7 +185,9 @@ export default class Tracking {
       originalUrl: window.location.href,
     });
 
-    window.snowplow('setCustomUrl', pageLinks.url);
+    const appendHash = ALLOWED_URL_HASHES.some((prefix) => window.location.hash.startsWith(prefix));
+    const customUrl = `${pageUrl}${appendHash ? window.location.hash : ''}`;
+    window.snowplow('setCustomUrl', customUrl);
 
     if (document.referrer) {
       const node = referrers.find((links) => links.originalUrl === document.referrer);

spec/frontend/tracking/tracking_spec.js

@@ -255,6 +255,23 @@ describe('Tracking', () => {
       expect(snowplowSpy).toHaveBeenCalledWith('setCustomUrl', TEST_HOST);
     });
 
+    describe('allowed hashes/fragments', () => {
+      it.each`
+        hash                  | appends  | description
+        ${'note_abc_123'}     | ${true}  | ${'appends'}
+        ${'diff-content-819'} | ${true}  | ${'appends'}
+        ${'first_heading'}    | ${false} | ${'does not append'}
+      `('$description `$hash` hash', ({ hash, appends }) => {
+        window.gl.snowplowPseudonymizedPageUrl = TEST_HOST;
+        window.location.hash = hash;
+
+        Tracking.setAnonymousUrls();
+
+        const url = appends ? `${TEST_HOST}#${hash}` : TEST_HOST;
+        expect(snowplowSpy).toHaveBeenCalledWith('setCustomUrl', url);
+      });
+    });
+
     it('does not set the referrer URL by default', () => {
       window.gl.snowplowPseudonymizedPageUrl = TEST_HOST;