feat(core): Update Testability to use PendingTasks for stability indicator

atscott · leonsenft · commit 9f479ae9641a · 2026-04-20T13:08:43.000-07:00
Since 12181b9, zone stability contributes to the PendingTasks. There is now a single source of truth for application stability tracked in PendingTasks. This change makes protractor's whenStable compatible with zoneless. The `Router` and `HttpClient` also contribute to stability using the `PendingTasks` injectable. There will likely be more updates in the future to have more features contribute to stableness in a zoneless compatible way. This update uses PendingTasks for stability by default when ZoneJS is not present or can be enabled with an option when ZoneJS is present (but otherwise ignored with ZoneJS). fixes #68180
diff --git a/goldens/public-api/platform-browser/index.api.md b/goldens/public-api/platform-browser/index.api.md
@@ -159,7 +159,9 @@ export const platformBrowser: (extraProviders?: StaticProvider[]) => PlatformRef
 export function provideClientHydration(...features: HydrationFeature<HydrationFeatureKind>[]): EnvironmentProviders;
 
 // @public
-export function provideProtractorTestingSupport(): Provider[];
+export function provideProtractorTestingSupport(options?: {
+    usePendingTasksForStability?: boolean;
+}): Provider[];
 
 // @public
 export const REMOVE_STYLES_ON_COMPONENT_DESTROY: InjectionToken<boolean>;
diff --git a/packages/core/src/core_private_export.ts b/packages/core/src/core_private_export.ts
@@ -153,6 +153,7 @@ export {_sanitizeUrl as ɵ_sanitizeUrl} from './sanitization/url_sanitizer';
 export {
   TESTABILITY as ɵTESTABILITY,
   TESTABILITY_GETTER as ɵTESTABILITY_GETTER,
+  USE_PENDING_TASKS as ɵUSE_PENDING_TASKS,
 } from './testability/testability';
 export {booleanAttribute, numberAttribute} from './util/coercion';
 export {devModeEqual as ɵdevModeEqual} from './util/comparison';
diff --git a/packages/core/src/testability/testability.ts b/packages/core/src/testability/testability.ts
@@ -6,9 +6,10 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
-import {inject, Inject, Injectable, InjectionToken} from '../di';
+import {Inject, Injectable, InjectionToken, inject} from '../di';
 import {isInInjectionContext} from '../di/contextual';
 import {DestroyRef} from '../linker/destroy_ref';
+import {PendingTasksInternal} from '../pending_tasks_internal';
 import {NgZone} from '../zone/ng_zone';
 
 /**
@@ -61,6 +62,14 @@ export const TESTABILITY = new InjectionToken<Testability>('');
  */
 export const TESTABILITY_GETTER = new InjectionToken<GetTestability>('');
 
+/**
+ * Internal injection token to signal whether to use pending tasks for stability.
+ */
+export const USE_PENDING_TASKS = new InjectionToken<boolean>('USE_PENDING_TASKS', {
+  providedIn: 'root',
+  factory: () => typeof Zone === 'undefined',
+});
+
 /**
  * The Testability service provides testing hooks that can be accessed from
  * the browser.
@@ -90,6 +99,8 @@ export class Testability implements PublicTestability {
 
   private _destroyRef?: DestroyRef;
 
+  private readonly pendingTasksInternal = inject(PendingTasksInternal);
+  private readonly _usePendingTasks = inject(USE_PENDING_TASKS);
   constructor(
     private _ngZone: NgZone,
     private registry: TestabilityRegistry,
@@ -121,20 +132,36 @@ export class Testability implements PublicTestability {
       },
     });
 
-    const onStableSubscription = this._ngZone.runOutsideAngular(() =>
-      this._ngZone.onStable.subscribe({
+    let pendingTasksSubscription: any;
+    let onStableSubscription: any;
+
+    this._ngZone.runOutsideAngular(() => {
+      if (this._usePendingTasks) {
+        pendingTasksSubscription = this.pendingTasksInternal.hasPendingTasksObservable.subscribe(
+          () => {
+            if (this.isStable()) {
+              this._ngZone.runOutsideAngular(() => {
+                this._runCallbacksIfReady();
+              });
+            }
+          },
+        );
+      }
+
+      onStableSubscription = this._ngZone.onStable.subscribe({
         next: () => {
           NgZone.assertNotInAngularZone();
           queueMicrotask(() => {
             this._isZoneStable = true;
             this._runCallbacksIfReady();
           });
         },
-      }),
-    );
+      });
+    });
 
     this._destroyRef?.onDestroy(() => {
       onUnstableSubscription.unsubscribe();
+      pendingTasksSubscription?.unsubscribe();
       onStableSubscription.unsubscribe();
     });
   }
@@ -143,7 +170,11 @@ export class Testability implements PublicTestability {
    * Whether an associated application is stable
    */
   isStable(): boolean {
-    return this._isZoneStable && !this._ngZone.hasPendingMacrotasks;
+    return (
+      this._isZoneStable &&
+      !this._ngZone.hasPendingMacrotasks &&
+      (!this._usePendingTasks || !this.pendingTasksInternal.hasPendingTasks)
+    );
   }
 
   private _runCallbacksIfReady(): void {
diff --git a/packages/core/test/bundling/forms_reactive/bundle.golden_symbols.json b/packages/core/test/bundling/forms_reactive/bundle.golden_symbols.json
@@ -267,6 +267,7 @@
       "TracingAction",
       "TracingService",
       "UNSET",
+      "USE_PENDING_TASKS",
       "USE_VALUE",
       "UnsubscriptionError",
       "VALID",
diff --git a/packages/core/test/bundling/forms_template_driven/bundle.golden_symbols.json b/packages/core/test/bundling/forms_template_driven/bundle.golden_symbols.json
@@ -261,6 +261,7 @@
       "TracingAction",
       "TracingService",
       "UNSET",
+      "USE_PENDING_TASKS",
       "USE_VALUE",
       "UnsubscriptionError",
       "VALID",
diff --git a/packages/core/test/testability/testability_spec.ts b/packages/core/test/testability/testability_spec.ts
diff --git a/packages/platform-browser/src/browser.ts b/packages/platform-browser/src/browser.ts
