fix(core): trigger ApplicationRef.destroy when Platform is destroyed (angular#46497)

This commit updates the `ApplicationRef` logic to trigger the destroy operation when an underlying platform is destroyed. This is needed to make sure all teardown processing is completed correctly to avoid memory leaks.

Closes angular#46473.

PR Close angular#46497

Author: AndrewKushnir

packages/core/src/application_ref.ts

@@ -60,7 +60,8 @@ export const ALLOW_MULTIPLE_PLATFORMS = new InjectionToken<boolean>('AllowMultip
  * `PlatformRef` class (i.e. register the callback via `PlatformRef.onDestroy`), thus making the
  * entire class tree-shakeable.
  */
-const PLATFORM_ON_DESTROY = new InjectionToken<() => void>('PlatformOnDestroy');
+const PLATFORM_DESTROY_LISTENERS =
+    new InjectionToken<Set<VoidFunction>>('PlatformDestroyListeners');
 
 const NG_DEV_MODE = typeof ngDevMode === 'undefined' || ngDevMode;
 
@@ -230,7 +231,18 @@ export function internalBootstrapApplication(config: {
         setLocaleId(localeId || DEFAULT_LOCALE_ID);
 
         const appRef = appInjector.get(ApplicationRef);
-        appRef.onDestroy(() => onErrorSubscription.unsubscribe());
+
+        // If the whole platform is destroyed, invoke the `destroy` method
+        // for all bootstrapped applications as well.
+        const destroyListener = () => appRef.destroy();
+        const onPlatformDestroyListeners = platformInjector.get(PLATFORM_DESTROY_LISTENERS, null);
+        onPlatformDestroyListeners?.add(destroyListener);
+
+        appRef.onDestroy(() => {
+          onPlatformDestroyListeners?.delete(destroyListener);
+          onErrorSubscription.unsubscribe();
+        });
+
         appRef.bootstrap(rootComponent);
         return appRef;
       });
@@ -303,7 +315,7 @@ export function createPlatformInjector(providers: StaticProvider[] = [], name?:
     name,
     providers: [
       {provide: INJECTOR_SCOPE, useValue: 'platform'},
-      {provide: PLATFORM_ON_DESTROY, useValue: () => _platformInjector = null},  //
+      {provide: PLATFORM_DESTROY_LISTENERS, useValue: new Set([() => _platformInjector = null])},
       ...providers
     ],
   });
@@ -523,8 +535,11 @@ export class PlatformRef {
     this._modules.slice().forEach(module => module.destroy());
     this._destroyListeners.forEach(listener => listener());
 
-    const destroyListener = this._injector.get(PLATFORM_ON_DESTROY, null);
-    destroyListener?.();
+    const destroyListeners = this._injector.get(PLATFORM_DESTROY_LISTENERS, null);
+    if (destroyListeners) {
+      destroyListeners.forEach(listener => listener());
+      destroyListeners.clear();
+    }
 
     this._destroyed = true;
   }

packages/core/test/bundling/animations/bundle.golden_symbols.json

@@ -354,13 +354,13 @@
     "name": "PARAM_REGEX"
   },
   {
-    "name": "PLATFORM_ID"
+    "name": "PLATFORM_DESTROY_LISTENERS"
   },
   {
-    "name": "PLATFORM_INITIALIZER"
+    "name": "PLATFORM_ID"
   },
   {
-    "name": "PLATFORM_ON_DESTROY"
+    "name": "PLATFORM_INITIALIZER"
   },
   {
     "name": "PlatformRef"

packages/core/test/bundling/forms_reactive/bundle.golden_symbols.json

@@ -357,13 +357,13 @@
     "name": "Optional"
   },
   {
-    "name": "PLATFORM_ID"
+    "name": "PLATFORM_DESTROY_LISTENERS"
   },
   {
-    "name": "PLATFORM_INITIALIZER"
+    "name": "PLATFORM_ID"
   },
   {
-    "name": "PLATFORM_ON_DESTROY"
+    "name": "PLATFORM_INITIALIZER"
   },
   {
     "name": "PlatformRef"

packages/core/test/bundling/forms_template_driven/bundle.golden_symbols.json

@@ -351,13 +351,13 @@
     "name": "Optional"
   },
   {
-    "name": "PLATFORM_ID"
+    "name": "PLATFORM_DESTROY_LISTENERS"
   },
   {
-    "name": "PLATFORM_INITIALIZER"
+    "name": "PLATFORM_ID"
   },
   {
-    "name": "PLATFORM_ON_DESTROY"
+    "name": "PLATFORM_INITIALIZER"
   },
   {
     "name": "PlatformRef"

packages/core/test/bundling/router/bundle.golden_symbols.json

@@ -432,13 +432,13 @@
     "name": "OutletInjector"
   },
   {
-    "name": "PLATFORM_ID"
+    "name": "PLATFORM_DESTROY_LISTENERS"
   },
   {
-    "name": "PLATFORM_INITIALIZER"
+    "name": "PLATFORM_ID"
   },
   {
-    "name": "PLATFORM_ON_DESTROY"
+    "name": "PLATFORM_INITIALIZER"
   },
   {
     "name": "PathLocationStrategy"

packages/core/test/bundling/standalone_bootstrap/bundle.golden_symbols.json

@@ -222,13 +222,13 @@
     "name": "Observable"
   },
   {
-    "name": "PLATFORM_ID"
+    "name": "PLATFORM_DESTROY_LISTENERS"
   },
   {
-    "name": "PLATFORM_INITIALIZER"
+    "name": "PLATFORM_ID"
   },
   {
-    "name": "PLATFORM_ON_DESTROY"
+    "name": "PLATFORM_INITIALIZER"
   },
   {
     "name": "R3Injector"

packages/platform-browser/test/browser/bootstrap_standalone_spec.ts

@@ -6,63 +6,60 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {DOCUMENT, ɵgetDOM as getDOM} from '@angular/common';
-import {Component, destroyPlatform, ErrorHandler, Inject, Injectable, InjectionToken, NgModule} from '@angular/core';
-import {inject} from '@angular/core/testing';
+import {Component, ErrorHandler, Inject, Injectable, InjectionToken, NgModule, PlatformRef} from '@angular/core';
+import {R3Injector} from '@angular/core/src/di/r3_injector';
+import {withBody} from '@angular/private/testing';
 
 import {bootstrapApplication, BrowserModule} from '../../src/browser';
 
 describe('bootstrapApplication for standalone components', () => {
-  let rootEl: HTMLUnknownElement;
-  beforeEach(inject([DOCUMENT], (doc: any) => {
-    rootEl = getDOM().createElement('test-app', doc);
-    getDOM().getDefaultDocument().body.appendChild(rootEl);
-  }));
-
-  afterEach(() => {
-    destroyPlatform();
-    rootEl?.remove();
-  });
-
   class SilentErrorHandler extends ErrorHandler {
     override handleError() {
       // the error is already re-thrown by the application ref.
       // we don't want to print it, but instead catch it in tests.
     }
   }
 
-  it('should create injector where ambient providers shadow explicit providers', async () => {
-    const testToken = new InjectionToken('test token');
+  it('should create injector where ambient providers shadow explicit providers',
+     withBody('<test-app></test-app>', async () => {
+       const testToken = new InjectionToken('test token');
 
-    @NgModule({
-      providers: [
-        {provide: testToken, useValue: 'Ambient'},
-      ]
-    })
-    class AmbientModule {
-    }
+       @NgModule({
+         providers: [
+           {provide: testToken, useValue: 'Ambient'},
+         ]
+       })
+       class AmbientModule {
+       }
 
-    @Component({
-      selector: 'test-app',
-      standalone: true,
-      template: `({{testToken}})`,
-      imports: [AmbientModule]
-    })
-    class StandaloneCmp {
-      constructor(@Inject(testToken) readonly testToken: String) {}
-    }
+       @Component({
+         selector: 'test-app',
+         standalone: true,
+         template: `({{testToken}})`,
+         imports: [AmbientModule]
+       })
+       class StandaloneCmp {
+         constructor(@Inject(testToken) readonly testToken: String) {}
+       }
 
-    const appRef = await bootstrapApplication(StandaloneCmp, {
-      providers: [
-        {provide: testToken, useValue: 'Bootstrap'},
-      ]
-    });
+       class SilentErrorHandler extends ErrorHandler {
+         override handleError() {
+           // the error is already re-thrown by the application ref.
+           // we don't want to print it, but instead catch it in tests.
+         }
+       }
 
-    appRef.tick();
+       const appRef = await bootstrapApplication(StandaloneCmp, {
+         providers: [
+           {provide: testToken, useValue: 'Bootstrap'},
+         ]
+       });
 
-    // make sure that ambient providers "shadow" ones explicitly provided during bootstrap
-    expect(rootEl.textContent).toBe('(Ambient)');
-  });
+       appRef.tick();
+
+       // make sure that ambient providers "shadow" ones explicitly provided during bootstrap
+       expect(document.body.textContent).toBe('(Ambient)');
+     }));
 
   /*
     This test verifies that ambient providers for the standalone component being bootstrapped
@@ -74,7 +71,7 @@ describe('bootstrapApplication for standalone components', () => {
     - standalone injector (ambient providers go here);
   */
   it('should create a standalone injector for standalone components with ambient providers',
-     async () => {
+     withBody('<test-app></test-app>', async () => {
        const ambientToken = new InjectionToken('ambient token');
 
        @NgModule({
@@ -119,10 +116,10 @@ describe('bootstrapApplication for standalone components', () => {
          expect(e).toBeInstanceOf(Error);
          expect((e as Error).message).toContain('No provider for InjectionToken ambient token!');
        }
-     });
+     }));
 
   it('should throw if `BrowserModule` is imported in the standalone bootstrap scenario',
-     async () => {
+     withBody('<test-app></test-app>', async () => {
        @Component({
          selector: 'test-app',
          template: '...',
@@ -145,10 +142,10 @@ describe('bootstrapApplication for standalone components', () => {
          expect((e as Error).message)
              .toContain('Providers from the `BrowserModule` have already been loaded.');
        }
-     });
+     }));
 
   it('should throw if `BrowserModule` is imported indirectly in the standalone bootstrap scenario',
-     async () => {
+     withBody('<test-app></test-app>', async () => {
        @NgModule({
          imports: [BrowserModule],
        })
@@ -177,5 +174,49 @@ describe('bootstrapApplication for standalone components', () => {
          expect((e as Error).message)
              .toContain('Providers from the `BrowserModule` have already been loaded.');
        }
-     });
+     }));
+
+  it('should trigger an app destroy when a platform is destroyed',
+     withBody('<test-app></test-app>', async () => {
+       let compOnDestroyCalled = false;
+       let serviceOnDestroyCalled = false;
+       let injectorOnDestroyCalled = false;
+
+       @Injectable({providedIn: 'root'})
+       class ServiceWithOnDestroy {
+         ngOnDestroy() {
+           serviceOnDestroyCalled = true;
+         }
+       }
+
+       @Component({
+         selector: 'test-app',
+         standalone: true,
+         template: 'Hello',
+       })
+       class ComponentWithOnDestroy {
+         constructor(service: ServiceWithOnDestroy) {}
+
+         ngOnDestroy() {
+           compOnDestroyCalled = true;
+         }
+       }
+
+       const appRef = await bootstrapApplication(ComponentWithOnDestroy);
+       const injector = (appRef as unknown as {injector: R3Injector}).injector;
+       injector.onDestroy(() => injectorOnDestroyCalled = true);
+
+       expect(document.body.textContent).toBe('Hello');
+
+       const platformRef = injector.get(PlatformRef);
+       platformRef.destroy();
+
+       // Verify the callbacks were invoked.
+       expect(compOnDestroyCalled).toBe(true);
+       expect(serviceOnDestroyCalled).toBe(true);
+       expect(injectorOnDestroyCalled).toBe(true);
+
+       // Make sure the DOM has been cleaned up as well.
+       expect(document.body.textContent).toBe('');
+     }));
 });