angular2 - 如何在 http.post 单元测试中模拟错误

Question

我正在编写一个带有 HTTP.post 调用的登录方法的 Uni-test，例如：

this.http.post( endpoint, creds, { headers: headers})
        .map(res => res.json())
        .subscribe(
        data => this.onLoginComplete(data.access_token, credentials),  
        err => this.onHttpLoginFailed(err),
        () => this.trace.debug(this.componentName, "Login completed.")
    );

问题是我无法模拟错误分支；每次调用 onLoginComplete 方法；

这是我的测试：

it("check that  Atfer Login, console show an error ", inject(
  [TraceService, Http, MockBackend, WsiEndpointService],
  (traceService: TraceService, http: Http, 
   backend: MockBackend, wsiEndpoint: WsiEndpointService) => {

  let tokenTest: number =  404 ;

  let response: ResponseOptions = null {} // i think i have to modify this

  let connection: any;

  backend.connections.subscribe((c: any) => connection = c);

  let authService: AuthService = new AuthService(http, Service1, Service2);

  authenticationservice.login({ "username": "a", "password": "1" });

  connection.mockRespond(new Response(response));

  expect(ERROR);

}));

再次感谢大家。

Answer 1

你可以模拟这样的错误：

connection.mockError(new Response(new ResponseOptions({
    body: '',
    status: 404,
})));

我创建了一个小班

import {ResponseOptions, Response} from '@angular/http';

export class MockError extends Response implements Error {

    name: any;
    message: any;

    constructor(status: number, body: string = '') {
        super(new ResponseOptions({status, body}));
    }
}

可以这样使用

connection.mockError(new MockError(404));

Answer 2

首先你需要用MockBackend 覆盖XHRBackend 类：

describe('HttpService Tests', () => {
  beforeEachProviders(() => {
    return [
      HTTP_PROVIDERS,
      provide(XHRBackend, { useClass: MockBackend }),
      HttpService
    ];
  });

  (...)
});

注意HttpService 是使用Http 对象的服务，我想测试。

然后你需要注入 mockBackend 并订阅它的 connections 属性。发送请求时，会调用相应的回调，您可以指定响应元素，如正文。服务将接收此响应作为调用的响应。因此，您将能够基于此测试您的服务方法。

下面我描述如何测试HttpService的getItems方法：

it('Should return a list of items', inject([XHRBackend, HttpService, Injector], (mockBackend, httpService, injector) => {
  mockBackend.connections.subscribe(
    (connection: MockConnection) => {
      connection.mockRespond(new Response(
        new ResponseOptions({
          body: [ { id: '1', label: 'item1' }]
        })));
      });

  httpService.getItems().subscribe(
    items => {
      expect(items).toEqual([ { id: '1', label: 'item1' }]);
    });
  });
});

这里是HttpService的getItems方法的代码：

@Injectable()
export class HttpService {
  constructor(private http:Http) {
  }

  getItems(): Observable<any[]> {
    return this.http.get('/items').map(res => res.json());
  }
}

要模拟错误，只需使用mockError 方法而不是mockResponseone：

  mockBackend.connections.subscribe(
    (connection: MockConnection) => {
      connection.mockError(new Error('some error'));
    });