Angular 7使用模拟http请求测试retryWhen无法实际重试

import { TestBed, inject } from '@angular/core/testing';
import { HttpClientTestingModule, HttpTestingController } from '@angular/common/http/testing';
import { HttpClient, HttpErrorResponse } from '@angular/common/http';
import { retryWhen } from 'rxjs/operators';

describe('HttpClientTestingModule', () => {
  let httpClient: HttpClient;
  let httpTestingController: HttpTestingController;

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

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

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

  it('should retry http request when retryWhen is used', () => {
    const url = 'https://api.example.com/data';

    // 设置模拟的http请求
    httpClient.get(url)
      .pipe(retryWhen(errors => errors))
      .subscribe(
        response => {
          // 断言请求成功的逻辑
          expect(response).toBeTruthy();
        },
        (error: HttpErrorResponse) => {
          // 断言请求失败的逻辑
          expect(error).toBeTruthy();
        }
      );

    // 模拟http请求
    const req = httpTestingController.expectOne(url);
    expect(req.request.method).toEqual('GET');

    // 返回一个错误响应
    req.flush('Error', { status: 500, statusText: 'Internal Server Error' });

    // 断言http请求被重试
    const retryReq = httpTestingController.expectOne(url);
    expect(retryReq.request.method).toEqual('GET');

    // 返回一个成功响应
    retryReq.flush({ data: 'Test Data' });
  });
});