angular - Angular 5 HttpClient HttpTestingController 测试错误路径

Question

我有一个服务可以发出如下的 HTTP 获取请求

  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);
  }

我有一个可以测试成功路径的测试规范。我如何能：

1. 让 HttpTestingController 出错以便调用 catchHttpError 函数？

2. 测试 _httpService.get 是否从 catchHttpError 函数中抛出错误？

到目前为止，我的测试看起来像：

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((objects: Object[]) => {
    actualObjects = objects;
  });

  backend.expectOne('/api/dummy/get/uri').flush(expectedObjects);
  expect(_httpService.get).toHaveBeenCalledTimes(1);
  expect(_httpService.get).toHaveBeenCalledWith('/api/dummy/get/uri');

  expect(actualObjects).toEqual(expectedObjects);
  expect(actualObjects.length).toBe(1);
  //expect(_httpService.get).toThrow();
})));

Answer 1

结束了这个。

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();
})));