Angular2测试http服务表示不支持映射功能

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

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

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

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

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

  it('should get data from API', () => {
    const mockData = { id: 1, name: 'John Doe' };

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

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