单元测试重试 websocket答案

【问题标题】：Unit testing retries websocket单元测试重试 websocket
【发布时间】：2019-11-28 11:42:43
【问题描述】：

我想对下面的函数进行单元测试，看看是否有 n 次 websocket 连接重试

ws = webSocket(url)

notification(action: string) {
    return this.ws.asObservable().pipe(
      retryWhen(errors =>
        errors.pipe(concatMap((_, iteration) =>
          timer(Math.pow(2, iteration) * 1000)),
          tap(e => console.log('test', e)),
          take(10))
      ),
      tap(e => console.log('st', e)),
      filter((e: any) => e.action === action));
  }

我对如何模拟 websocket 有点困惑

it('should make call 10 times', fakeAsync(() => {
    const service = TestBed.get(NotificationService);
    let wsSpy = new Subject()
    service.ws = wsSpy;
    service.filterNotification('test').subscribe(data => {
      expect(data).toBe('data')
    })
    wsSpy.error({ action: 'test' })
    tick(time)
    wsSpy.error({ action: 'test' })
    // sending error the first time cancels the subscription
    // Is there any other way to send the error many times
    wsSpy.next({ action: 'test' })
  }));

【问题讨论】：

标签： angular unit-testing jasmine

【解决方案1】：

为了模拟失败的 websocket，我创建了以下函数来关闭重试次数

function mockWs() {
  let i = 0;
  return function () {
    return Observable.create((obs: Observer<any>) => {
      i++;
      if (i < 10) {
        obs.error(new Error('attempt' + i));
      } else {
        obs.next(mockData);
        obs.complete();
      }

    })
  }
}
const wsMockSpy = mockWs();

然后，我不得不监视对象的属性 asObservable 以提供模拟

spyOn(service.ws, 'asObservable').and.callFake(wsMockSpy);

整个单元测试如下

it('should try multiple times', fakeAsync(() => {
    service = TestBed.get(NotificationService);
    const mockData = { action: 'testMultiple' };
    function mockWs() {
      let i = 0;
      return function () {
        return Observable.create((obs: Observer<any>) => {
          i++
          console.log('i', i)
          if (i < 10) {
            obs.error(new Error('val' + i));
          } else {
            obs.next(mockData);
            obs.complete();
          }

        })
      }
    }
    const wsMockSpy = mockWs();
    spyOn(service.ws, 'asObservable').and.callFake(wsMockSpy);

    service.notification('testMultiple').subscribe(data => {
      expect(data).toEqual(mockData)
    })
    tick(1230000)
  }) )

【讨论】：