feat(service-worker): Logs unhandled promise rejections in service worker (#63059)

Adds handling and logging for unhandled promise rejections to improve debugging and prevent silent failures. Updates tests and test harness to verify logging of rejection reasons

PR Close #63059

Author: SkyZeroZx

packages/service-worker/worker/src/driver.ts

@@ -204,7 +204,8 @@ export class Driver implements Debuggable, UpdateSource {
     });
 
     // Handle the fetch, message, push, notificationclick,
-    // notificationclose, pushsubscriptionchange, and messageerror events.
+    // notificationclose, pushsubscriptionchange, messageerror, rejectionhandled,
+    // and unhandledrejection events.
     this.scope.addEventListener('fetch', (event) => this.onFetch(event!));
     this.scope.addEventListener('message', (event) => this.onMessage(event!));
     this.scope.addEventListener('push', (event) => this.onPush(event!));
@@ -216,6 +217,7 @@ export class Driver implements Debuggable, UpdateSource {
       this.onPushSubscriptionChange(event as PushSubscriptionChangeEvent),
     );
     this.scope.addEventListener('messageerror', (event) => this.onMessageError(event));
+    this.scope.addEventListener('unhandledrejection', (event) => this.onUnhandledRejection(event));
 
     // The debugger generates debug pages in response to debugging requests.
     this.debugger = new DebugHandler(this, this.adapter);
@@ -362,6 +364,15 @@ export class Driver implements Debuggable, UpdateSource {
     );
   }
 
+  private onUnhandledRejection(event: PromiseRejectionEvent): void {
+    // Handle unhandled promise rejections in the service worker.
+    // This is for debugging and preventing silent failures.
+    this.debugger.log(
+      `Unhandled promise rejection occurred`,
+      `Driver.onUnhandledRejection(reason: ${event.reason})`,
+    );
+  }
+
   private async ensureInitialized(event: ExtendableEvent): Promise<void> {
     // Since the SW may have just been started, it may or may not have been initialized already.
     // `this.initialized` will be `null` if initialization has not yet been attempted, or will be a

packages/service-worker/worker/test/happy_spec.ts

@@ -1208,6 +1208,21 @@ import {envIsSupported} from '../testing/utils';
       });
     });
 
+    describe('unhandledrejection events', () => {
+      it('logs unhandled promise rejection errors', async () => {
+        await driver.initialized;
+
+        const debuggerLogSpy = spyOn(driver.debugger, 'log');
+
+        scope.handleUnhandledRejection('Test rejection reason');
+
+        expect(debuggerLogSpy).toHaveBeenCalledWith(
+          'Unhandled promise rejection occurred',
+          'Driver.onUnhandledRejection(reason: Test rejection reason)',
+        );
+      });
+    });
+
     describe('notification close events', () => {
       it('broadcasts notification close events', async () => {
         expect(await makeRequest(scope, '/foo.txt')).toEqual('this is foo');

packages/service-worker/worker/testing/scope.ts

@@ -281,6 +281,17 @@ export class SwTestHarnessImpl
     return event.ready;
   }
 
+  handleUnhandledRejection(reason: any): void {
+    if (!this.eventHandlers.has('unhandledrejection')) {
+      throw new Error('No unhandledrejection handler registered');
+    }
+    const event = {
+      reason,
+      promise: Promise.reject(reason),
+    } as PromiseRejectionEvent;
+    this.eventHandlers.get('unhandledrejection')!.call(this, event);
+  }
+
   override timeout(ms: number): Promise<void> {
     const promise = new Promise<void>((resolve) => {
       this.timers.push({