在Angular 6中使用HTTP请求测试服务方法

import { TestBed, inject } from '@angular/core/testing';
import { HttpClientTestingModule, HttpTestingController } from '@angular/common/http/testing';

import { DataService } from './data.service';

describe('DataService', () => {
  let service: DataService;
  let httpMock: HttpTestingController;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [HttpClientTestingModule],
      providers: [DataService]
    });

    service = TestBed.inject(DataService);
    httpMock = TestBed.inject(HttpTestingController);
  });

  afterEach(() => {
    httpMock.verify();
  });

  it('should retrieve data from the API via GET', () => {
    const dummyData = { id: 1, name: 'John Doe' };

    service.getData().subscribe(data => {
      expect(data).toEqual(dummyData);
    });

    const req = httpMock.expectOne('api/data');
    expect(req.request.method).toBe('GET');
    req.flush(dummyData);
  });
});