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

/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.dev/license
 */

import {
  Component,
  destroyPlatform,
  ErrorHandler,
  Inject,
  Injectable,
  InjectionToken,
  NgModule,
  NgZone,
  PlatformRef,
  ɵR3Injector as R3Injector,
  ɵNoopNgZone as NoopNgZone,
} from '@angular/core';
import {withBody} from '@angular/private/testing';

import {bootstrapApplication, BrowserModule} from '../../src/browser';

describe('bootstrapApplication for standalone components', () => {
  beforeEach(destroyPlatform);
  afterEach(destroyPlatform);

  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',
    withBody('<test-app></test-app>', async () => {
      const testToken = new InjectionToken('test token');

      @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) {}
      }

      const appRef = await bootstrapApplication(StandaloneCmp, {
        providers: [{provide: testToken, useValue: 'Bootstrap'}],
      });

      appRef.tick();

      // make sure that ambient providers "shadow" ones explicitly provided during bootstrap
      expect(document.body.textContent).toBe('(Ambient)');
    }),
  );

  it(
    'should be able to provide a custom zone implementation in DI',
    withBody('<test-app></test-app>', async () => {
      @Component({
        selector: 'test-app',
        standalone: true,
        template: ``,
      })
      class StandaloneCmp {}

      class CustomZone extends NoopNgZone {}
      const instance = new CustomZone();

      const appRef = await bootstrapApplication(StandaloneCmp, {
        providers: [{provide: NgZone, useValue: instance}],
      });

      appRef.tick();
      expect(appRef.injector.get(NgZone)).toEqual(instance);
    }),
  );

  /*
    This test verifies that ambient providers for the standalone component being bootstrapped
    (providers collected from the import graph of a standalone component) are instantiated in a
    dedicated standalone injector. As the result we are ending up with the following injectors
    hierarchy:
    - platform injector (platform specific providers go here);
    - application injector (providers specified in the bootstrap options go here);
    - standalone injector (ambient providers go here);
  */
  it(
    'should create a standalone injector for standalone components with ambient providers',
    withBody('<test-app></test-app>', async () => {
      const ambientToken = new InjectionToken('ambient token');

      @NgModule({
        providers: [{provide: ambientToken, useValue: 'Only in AmbientNgModule'}],
      })
      class AmbientModule {}

      @Injectable()
      class NeedsAmbientProvider {
        constructor(@Inject(ambientToken) readonly ambientToken: String) {}
      }

      @Component({
        selector: 'test-app',
        template: `({{service.ambientToken}})`,
        standalone: true,
        imports: [AmbientModule],
      })
      class StandaloneCmp {
        constructor(readonly service: NeedsAmbientProvider) {}
      }

      try {
        await bootstrapApplication(StandaloneCmp, {
          providers: [{provide: ErrorHandler, useClass: SilentErrorHandler}, NeedsAmbientProvider],
        });

        // we expect the bootstrap process to fail since the "NeedsAmbientProvider" service
        // (located in the application injector) can't "see" ambient providers (located in a
        // standalone injector that is a child of the application injector).
        fail('Expected to throw');
      } catch (e: unknown) {
        expect(e).toBeInstanceOf(Error);
        expect((e as Error).message).toContain(
          'NG0201: No provider found for `InjectionToken ambient token`. ' +
            'Source: Standalone[StandaloneCmp]. ' +
            'Path: NeedsAmbientProvider -> InjectionToken ambient token. ' +
            'Find more at https://angular.dev/errors/NG0201',
        );
      }
    }),
  );

  it(
    'should throw if `BrowserModule` is imported in the standalone bootstrap scenario',
    withBody('<test-app></test-app>', async () => {
      @Component({
        selector: 'test-app',
        template: '...',
        standalone: true,
        imports: [BrowserModule],
      })
      class StandaloneCmp {}

      try {
        await bootstrapApplication(StandaloneCmp, {
          providers: [{provide: ErrorHandler, useClass: SilentErrorHandler}],
        });

        // The `bootstrapApplication` already includes the set of providers from the
        // `BrowserModule`, so including the `BrowserModule` again will bring duplicate
        // providers and we want to avoid it.
        fail('Expected to throw');
      } catch (e: unknown) {
        expect(e).toBeInstanceOf(Error);
        expect((e as Error).message).toContain(
          'NG05100: Providers from the `BrowserModule` have already been loaded.',
        );
      }
    }),
  );

  it(
    'should throw if `BrowserModule` is imported indirectly in the standalone bootstrap scenario',
    withBody('<test-app></test-app>', async () => {
      @NgModule({
        imports: [BrowserModule],
      })
      class SomeDependencyModule {}

      @Component({
        selector: 'test-app',
        template: '...',
        standalone: true,
        imports: [SomeDependencyModule],
      })
      class StandaloneCmp {}

      try {
        await bootstrapApplication(StandaloneCmp, {
          providers: [{provide: ErrorHandler, useClass: SilentErrorHandler}],
        });

        // The `bootstrapApplication` already includes the set of providers from the
        // `BrowserModule`, so including the `BrowserModule` again will bring duplicate
        // providers and we want to avoid it.
        fail('Expected to throw');
      } catch (e: unknown) {
        expect(e).toBeInstanceOf(Error);
        expect((e as Error).message).toContain(
          'NG05100: 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('');
    }),
  );
});