我想测试一个使用异步管道的组件。这是我的代码:@Component({selector:'test',template:`{{number|async}}`})classAsyncComponent{number=Observable.interval(1000).take(3)}fdescribe('AsyncCompnent',()=>{letcomponent:AsyncComponent;letfixture:ComponentFixture;beforeEach(async(()=>{TestBed.configureTestingModule({declarations:[