如何使用HttpTestingController刷新标题？

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

let httpTestingController: HttpTestingController;

beforeEach(() => {
  TestBed.configureTestingModule({
    imports: [HttpClientTestingModule],
    providers: [YourService] // 替换为你的服务名称
  });

  httpTestingController = TestBed.inject(HttpTestingController);
});

it('should refresh title using HttpTestingController', inject([YourService], (service: YourService) => {
  const expectedTitle = 'New Title';

  // 发送GET请求
  service.refreshTitle().subscribe(() => {
    // 请求完成后的回调函数
    expect(document.title).toBe(expectedTitle); // 验证标题是否刷新成功
  });

  const req = httpTestingController.expectOne('/api/title'); // 期望发送的请求

  expect(req.request.method).toBe('GET'); // 验证请求方法是否为GET

  // 模拟响应
  req.flush({ title: expectedTitle });

  httpTestingController.verify(); // 验证没有其他未处理的请求
}));