Angular 测试期间 Karma 的反向代理配置

### Angular 中使用 Karma 的反向代理配置

javascript
module.exports = function(config) {
  config.set({
    // ...其他配置项
    proxies: {
      // 将 '/api' 路径下的请求代理到指定的目标地址
      '/api': {
        'target': 'http://localhost:3000', // 目标地址
        'changeOrigin': true,
        'secure': false
      }
    },
    // ...其他配置项
  });
};

typescript
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
@Injectable()
export class DataService {
  constructor(private http: HttpClient) {}
  fetchData() {
    return this.http.get('/api/data'); // 发送至 '/api/data' 的请求
  }
}

typescript
describe('DataService', () => {
  let service: DataService;
  let httpMock: HttpTestingController;
  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [DataService],
      imports: [HttpClientTestingModule]
    });
    service = TestBed.inject(DataService);
    httpMock = TestBed.inject(HttpTestingController);
  });
  it('should fetch data via proxy', () => {
    const testData = { message: 'Test data' };
    service.fetchData().subscribe(data => {
      expect(data).toEqual(testData);
    });
    const req = httpMock.expectOne('/api/data'); // 期望请求被代理至 '/api/data'
    expect(req.request.method).toBe('GET');
    req.flush(testData); // 模拟返回测试数据
  });
  afterEach(() => {
    httpMock.verify();
  });
});