Angular 角度5 HttpClient HttpTestingController测试错误路径

我有一个服务，它发出HTTP get请求，如下所示

  public get(uri: string, params?: HttpParams): Observable<Object> {
    return params ? this._http.get(uri, { params: params }) : this._http.get(uri)
      .catch((error: HttpErrorResponse) => this.catchHttpError(error));
  }

  private catchHttpError(error: HttpErrorResponse) : Observable<Object> {
    this._logger.error(`error occurred: ${error.message}`);
    throw(error);
  }

---

最后还是这样

it('should make a get request and catch error', async(inject([HttpService, HttpTestingController], (_httpService: HttpService, backend: HttpTestingController) => {
  spyOn(_httpService, 'get').and.callThrough();
  let actualObjects: Object[] = [];
  _httpService.get('/api/dummy/get/uri').subscribe(null, (response: HttpErrorResponse) => {
    expect(response.message).toBe('Http failure response for /api/dummy/get/uri: 500 Server Error');
  });

  backend.expectOne('/api/dummy/get/uri').flush(expectedObjects, { status: 500, statusText: 'Server Error' });
  expect(_httpService.get).toHaveBeenCalledTimes(1);
  expect(_httpService.get).toHaveBeenCalledWith('/api/dummy/get/uri');

  expect(actualObjects).toBeNull();
})));

it('should make a get request and catch error', async(inject([HttpService, HttpTestingController], (_httpService: HttpService, backend: HttpTestingController) => {
  spyOn(_httpService, 'get').and.callThrough();
  let actualObjects: Object[] = [];
  _httpService.get('/api/dummy/get/uri').subscribe(null, (response: HttpErrorResponse) => {
    expect(response.message).toBe('Http failure response for /api/dummy/get/uri: 500 Server Error');
  });

  backend.expectOne('/api/dummy/get/uri').flush(expectedObjects, { status: 500, statusText: 'Server Error' });
  expect(_httpService.get).toHaveBeenCalledTimes(1);
  expect(_httpService.get).toHaveBeenCalledWith('/api/dummy/get/uri');

  expect(actualObjects).toBeNull();
})));