用Jest / Angular进行可观察的单元测试

Question

我创建了一个具有多个流依赖级别的组件。尝试为此页面编写单元测试时，我不断收到错误消息Timeout - Async callback was not invoked within the 5000ms timeout specified by jest.setTimeout。寻找有关如何使我的观察对象调用的建议。

下面是该组件和相关测试的一些示例代码。

组件：

export class DashboardComponent implements OnInit {
  public _foo = new Subject();
  public foo$: Observable<IFoo[]> = this._foo.pipe(
    tap(() => { this.loading = true; },
    switchMap((id: number) => this.mySvc.getFoo(id)),
    shareReplay(1)
  );
  public bar$: Observable<IBar[]> = this.foo$.pipe(
    switchMap((foo: IFoo) => this.mySvc.getBar(foo.id),
    shareReplay(1)
  );
}

测试bar$：

it('should get bar', done => {
  component.foo$ = of(MockFooArray); // Set the dependency observable

  jest.spyOn(component['service'], 'getBar').mockReturnValue(of(MockBarArray));

  component.bar$.subscribe(() => {
    expect.assertions(3);
    // assertions
    done();
  });
});