Update test/specs/offline/service-worker.spec.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: stefanhuber

test/specs/offline/service-worker.spec.ts

@@ -44,7 +44,13 @@ describe('Service Worker Offline Support', () => {
       // Reset hash router state and reload so the SW intercepts all requests
       await sw.freshReload();
       await languagePage.waitForPage();
-      await browser.pause(2000);
+      await browser.waitUntil(
+        async () => await sw.isCached('data.json'),
+        {
+          timeout: 30000,
+          timeoutMsg: 'data.json was not cached by the service worker within 30s',
+        }
+      );
     });
 
     it('caches data.json after SW-controlled load', async () => {