Angular：使用MockBackend测试HTTP，是否真的需要async（）？

Question

我使用MockBackend来测试依赖于@angular/http的代码 Web上的所有示例都使用异步测试设置，如下所示：
thoughtram: Testing Services with Http in Angular

describe('getVideos()', () => {

  it('should return an Observable<Array<Video>>',
      async(inject([VideoService, MockBackend], (videoService, mockBackend) => {

      videoService.getVideos().subscribe((videos) => {
        expect(videos.length).toBe(4);
        expect(videos[0].name).toEqual('Video 0');
        expect(videos[1].name).toEqual('Video 1');
        expect(videos[2].name).toEqual('Video 2');
        expect(videos[3].name).toEqual('Video 3');

        expect("THIS TEST IS FALSE POSITIVE").toEqual(false); 
      });

      const mockResponse = {
        data: [
          { id: 0, name: 'Video 0' },
          { id: 1, name: 'Video 1' },
          { id: 2, name: 'Video 2' },
          { id: 3, name: 'Video 3' }
        ]
      };

      mockBackend.connections.subscribe((connection) => {
        connection.mockRespond(new Response(new ResponseOptions({
          body: JSON.stringify(mockResponse)
        })));
      });
  })));
});

然而，我试过了，我很确定MockBackend执行完全同步：

describe('getVideos()', () => {

  it('should return an Observable<Array<Video>>',
    inject([VideoService, MockBackend], (videoService, mockBackend) => {

      const mockResponse = {
        data: [
          { id: 0, name: 'Video 0' },
          { id: 1, name: 'Video 1' },
          { id: 2, name: 'Video 2' },
          { id: 3, name: 'Video 3' },
        ]
      };

      mockBackend.connections.subscribe((connection) => {
        connection.mockRespond(new Response(new ResponseOptions({
          body: JSON.stringify(mockResponse)
        })));
      });

      let videos;
      videoService.getVideos().subscribe(v => videos = v);

      // synchronous code!?
      expect(videos.length).toBe(4);
      expect(videos[0].name).toEqual('Video 0');
      expect(videos[1].name).toEqual('Video 1');
      expect(videos[2].name).toEqual('Video 2');
      expect(videos[3].name).toEqual('Video 3');
    }));
});

我在这里创建了一个关于plunker的完整示例： https://plnkr.co/edit/I3N9zL?p=preview

自撰写这些文章以来，必须改变一些东西。 有人能指出我那个突破性的变化吗？或者我错过了一个重要的事实？

Answer 1

你完全正确的假设，MockConnection.mockRespond()发出同步。在这个特定的测试中不需要async()。

我是您在问题中提及的文章的作者，我已相应更新了该文章。

非常感谢您指出这一点！