使用 jasmine/karma 和 http post mocking 进行 Angular 4 单元测试 - 如何修复

Question

我有一项服务，我想在 angular 4 typescript jasmine 中进行单元测试。

现在，http 正在做一个 post ，它返回一个身份，但是..它没有发送任何东西。

我只想拥有良好的代码覆盖率，但我不明白如何完成这个模拟语句。

这是我的服务文件中的http post方法

addSession() {
        let headers = new Headers({ 'Content-Type': 'application/json' });
        let options = new RequestOptions({ headers: headers });

        return this.http.post(this.url, JSON.stringify({}), options)
            .map((response: Response) => response.json());

}

然后是 SPEC 文件 ，我不知道要真正测试什么，我想假装我从服务 http post 收到了一个数字，响应应该类似于 000000014

规范

import { TrackerFormService } from './tracker-form.service'
import { Observable } from 'rxjs/Observable'

describe('TrackerFormService', () => {

    let trackerFormService: TrackerFormService,
        mockHttp;

    beforeEach(() => {
        mockHttp = jasmine.createSpyObj('mockHttp', ['get', 'post', 'put']
        )
        trackerFormService = new TrackerFormService(mockHttp);
    });

    describe('addSession', () => {

        it('add session ', () => {
              // how to test,  what to test?    
              // response , is a number?  how to mock/fake this?

        })

    })

})

Answer 1

为了实现你想要的，你需要的模拟是一个简单的函数，它返回与 POST 正常执行的相同的函数；另一件事是你的测试不应该真正命中服务器，所以你需要这样的东西(你可能需要添加其他依赖项):

import { HttpModule } from '@angular/http';
import { TrackerFormService } from './tracker-form.service'
import { Observable } from 'rxjs/Observable'

describe('TrackerFormService', () => {
// Mock the service like this and add all the functions you have in this fashion
let trackerFormService: TrackerFormService,
  mockService = {
    addSession: jasmine.createSpy('addSession').and.returnValue(Observable.of('your session object mock goes here'))
  };

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [HttpModule],
      providers: [{
        provide: TrackerFormService,
        useValue: mockService
      }]
    });
  });

  // Do this trick to inject the service every time, and just use `service` in your tests
  beforeEach(inject([TrackerFormService], (trackerFormService) => {
    service = trackerFormService;
  }));

  describe('addSession', () => {
    it('add session ', () => {
      let fakeResponse = null;

      // Call the service function and subscribe to it to catch the fake response coming from the mock.
      service.addSession().subscribe((value) => {
        // in here value will be whatever you put as returnValue (remember to keep the observable.of())
        fakeResponse = value;
      });

      // expects as in any test.
      expect(fakeResponse).toBeDefined();
      expect(fakeResponse).toBe('your session object mock goes here');
    });
  });
});