Angular 5- Jasmine测试:模拟对实际HTTP请求的错误响应

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

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

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [HttpClientTestingModule],
      providers: [MyService]
    });
    service = TestBed.inject(MyService);
    httpMock = TestBed.inject(HttpTestingController);
  });

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

  it('should handle error response', () => {
    const mockErrorResponse = { status: 400, statusText: 'Bad Request' };
    const mockError = new ErrorEvent('Network error', mockErrorResponse);

    service.getData().subscribe(
      data => fail('Expected an error, but received data'),
      error => {
        expect(error).toBe('Error: Network error');
      }
    );

    const req = httpMock.expectOne('api/data');
    req.error(mockError);
  });
});