视图提供程序中提供测试床时如何使用测试床获取提供程序实例

Question

我试图通过监视来测试我的单元测试中是否已调用了服务。该服务由视图提供程序中的父组件提供给我的组件。

间谍似乎无法正常工作，并调用了服务类中的真实方法。我相信它与我作为视图提供者提供的服务有关，并且我无法获得要监视的服务的正确实例……有人知道我如何获得要监视的类的正确实例吗？我知道我可能会取消该服务，但我希望有一个更好的解决方案。

@Component({
  selector: 'child-selector',
  templateUrl: 'child.component.html'
})
export class Component implements OnInit {

  constructor(
    readonly service: TheService
  ) {}


  onSubmit() {
    this.service.doThing();
  }
}

@Component({
  selector: 'container',
  template: `
    <child-selector
    ></child-selector>
  `,
  viewProviders: [The Service]
})
export class ParentComponent {
}

describe('Componet => ', () => {
  let fixture;
  let componentInstance;
  let debugElement: DebugElement;
  let service;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [
        CommonModule,
        HttpClientTestingModule,
        ReactiveFormsModule
      ],
      providers: [
        FormBuilder,
        TheService,
      ],
      schemas: [NO_ERRORS_SCHEMA]
    }).compileComponents().then(() => {

      fixture = TestBed.createComponent(Component);
      componentInstance = fixture.componentInstance;
      debugElement = fixture.debugElement;
      
      // service = TestBed.get(TheService);
      service = debugElement.injector.get(TheService);
    });
  }));

  it('should call service to do thing ', () => {
    spyOn(service, 'doThing');

    componentInstance.onSubmit(formThing);

    expect(service.doThing).toHaveBeenCalledTimes(1);
  });
});