Angular w/Jest : `verify()` vs .`expectOne()` ?

Question

我有一个失败的测试，我不确定如何修复。我从 Jest 得到的错误消息似乎是矛盾的，问题与两个 Angular HttpTestingController 的行为有关。方法:verify() 和 expectOne()。

有问题的测试，在其文件的上下文中:

import {TestBed, getTestBed} from '@angular/core/testing';
import {HttpClientTestingModule, HttpTestingController} from '@angular/common/http/testing';
import {PrintProjectsService} from './print-projects.service';
import {AppConfig} from '../../app.config';

describe('PrintProjectsService', () => {
  let injector: TestBed;
  let service: PrintProjectsService;
  let appConfig: AppConfig;
  let httpMock: HttpTestingController;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [HttpClientTestingModule],
      providers: [PrintProjectsService, AppConfig]
    });
    injector = getTestBed();
    service = injector.get(PrintProjectsService);
    httpMock = injector.get(HttpTestingController);
    appConfig = injector.get(AppConfig);
  });

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

  //This test passes
  it('should make a GET request to retrieve a printable factory when provided a printable factory id', () => {
    const id = '12345';
    service.getPrintableFactory(id).subscribe();
    const req = httpMock.expectOne(`${appConfig.API_URL}/api/printed-book/v1/printable-factories/${id}/`);
    expect(req.request.method).toBe('GET');
  });

  // This is the one that fails
  it('should make a GET request to retrieve cover image data from the cover service', () => {
    const imageType = 'full';
    service.getCoverImage(12345, '0850X1100FCSTDCO080CW444GXX', imageType).subscribe();
    //httpMock.verify(); //this finds a GET at undefined/cover/api/cover-images/full
    const req = httpMock.expectOne(`${appConfig.API_URL}/cover/api/cover-images/${imageType}`);
    expect(req.request.responseType).toBe('blob');
  });
});

Jest 返回此错误消息:

● PrintProjectsService › should make a GET request to retrieve cover image data from the cover service

Expected one matching request for criteria "Match URL: undefined/cover/api/cover-images/full", found none.

  44 |     service.getCoverImage(12345, '0850X1100FCSTDCO080CW444GXX', imageType).subscribe();
> 45 |     const req = httpMock.expectOne(`${appConfig.API_URL}/cover/api/cover-images/${imageType}`);
  46 |     expect(req.request.responseType).toBe('blob');

  at HttpClientTestingBackend.Object.<anonymous>.HttpClientTestingBackend.expectOne (node_modules/@angular/common/bundles/common-http-testing.umd.js:435:19)
  at src/app/services/print-projects/print-projects.service.spec.ts:45:26
  ...
  at Object.testBody.length (node_modules/jest-zone-patch/index.js:50:27)

● PrintProjectsService › should make a GET request to retrieve cover image data from the cover service

Expected no open requests, found 1: GET undefined/cover/api/cover-images/full

  23 |   afterEach(() => {
> 24 |     httpMock.verify();
  25 |   });

错误消息中 URL 变量呈现为 undefined 的事实是无关紧要的 - 在通过的测试中也是如此。

令我困惑的是，当测试中到达expectOne()时，找不到undefined/cover/api/cover-images/full的请求，但在测试之后，verify() 在 相同 URL 处发现了一个 GET 请求:undefined/cover/api/cover-images/full。 verify() 还在 expectOne().

为什么 expectOne() 没有捕获到请求，而 verify() 却捕获了请求？错误消息没有告诉我我需要的一切吗？无论我运行 jest 还是 jest --verbose，我似乎都会收到相同的错误消息。

Answer 1

我找到了解决此问题的方法，使用从此处收集的 expectOne() 变体:https://github.com/thymikee/jest-preset-angular/blob/master/example/src/app/service/hero.service.spec.ts#L59

这是通过测试的新版本:

it('should make a GET request to retrieve cover image data from the cover service', () => {
    const imageType = 'full';
    service.getCoverImage(12345, '0850X1100FCSTDCO080CW444GXX', imageType).subscribe();
    const req = httpMock.expectOne((request: HttpRequest<Blob>) => {
      return request.url === `${appConfig.API_URL}/cover/api/cover-images/${imageType}`;
    });
    expect(req.request.method).toBe('GET');
    // the original `expect()` below also passes, but since we already state that the request will return a Blob above, the `expect()` above is a better option
    // expect(req.request.responseType).toBe('blob'); 
  });

看起来好像 expectOne() 的 url 只匹配版本，正如最初使用的那样，期望一个 JSON 响应默认。无论如何，这个特定调用的 Blob 响应类型似乎是问题的根源。