如何用 jasmine-marbles 测试 forkJoin() 运算符

Question

我创建了向后端发送数据的服务，数据由用户在 UI 中填写。用户还可以上传任何文件以将其发送到后端。我正在尝试用茉莉花弹珠测试此功能。

这是我的服务代码：

export class FormSubmitService {
  constructor(private http: HttpClient) {}

  public submit(data, attachments) {
    const observables = [
      ...attachments.map((file) => this.uploadAttachment(file)),
    ];

    return forkJoin(...observables)
      .pipe(
        defaultIfEmpty([]),
        map((tokens) => {
          return tokens.map((tokenObj) => tokenObj.attachment_token);
        }),
        switchMap((tokens: string[]) => {
          const formData = {
            data,
            attachments: tokens,
          };

          return this.submitForm(formData);
        }),
      );
  }

  private uploadAttachment(attachment: File) {
    const attachmentData: FormData = new FormData();
    attachmentData.append('attachment', attachment, attachment.name);

    return this.http.post(
      '/some/form/endpoint/attachments',
      attachmentData,
    );
  }

  private submitForm(userData: UserData) {
    return this.http.post(
      `/some/form/endpoint/form`,
      userData,
    );
  }
}

如果用户添加一个或多个附件，那么在我将用户数据发送到后端之前，我需要将每个附件上传到后端以获取每个附件的令牌，稍后我将其存储在数组中。我正在使用 forkJoin() 进行操作，等待所有附件上传完毕，然后使用 switchMap 提交用户数据。

这是我的两个测试用例（一个工作，一个不工作）：

describe('SubmitFormData', () => {
  let service: FormSubmitService;
  let http: jasmine.SpyObj<HttpClient>;

  beforeEach(() => {
    http = jasmine.createSpyObj('HttpClient', ['post']);
    service = new FormSubmitService(http);
  });

  describe('#submit', () => {
    const file = new File([''], 'filename', { type: 'image/png' });
    const attachments = [file];
    const data = {
      name: 'name',
      description: 'description',
    };

    // NOT WORKING!
    it('submit with attachment', () => {
      const expected = cold('-a--b-', { a: ['token'], b: { id: 'id_123' } }); // FAIL!
      // const expected = cold('----'); // SUCCESS!
      http.post.and.returnValues(
        cold('-a-', { a: [{ attachment_token: 'token' }] }),
        cold('-a-', { a: { id: 'id_123' } }),
      );

      const output = service.submit(data, attachments);

      expect(output).toBeObservable(expected);
      expect(http.post).toHaveBeenCalled();
    });

    // WORKING!
    it('submit without attachment', () => {
      const response = {
        id: 'id_123',
      };
      const expected = cold('-a-', { a: response });
      http.post.and.returnValues(
        cold('-a-', { a: { id: 'id_123' } }),
      );

      const output = service.submit(data, []);

      expect(output).toBeObservable(expected);
      expect(http.post).toHaveBeenCalled();
    });
  });
});

测试无附件的表单数据成功，但测试有附件的表单数据失败。

失败的错误消息：

✖ submit with attachment HeadlessChrome 71.0.3578 (Mac OS X 10.14.2) Error: Expected $.length = 0 to equal 2. Expected $[0] = undefined to equal Object({ frame: 10, notification: Notification({ kind: 'N', value: [ 'token' ], error: undefined, hasValue: true }) }). Expected $[1] = undefined to equal Object({ frame: 40, notification: Notification({ kind: 'N', value: Object({ id: 'id_123' }), error: undefined, hasValue: true }) }).

似乎 output 在失败的测试中没有发出 observable 而是 undefined，但问题是 - 为什么？因为在另一个测试中，它在不发送附件并使用 forkJoin().

时发出它

有人知道为什么会这样吗？谢谢！

Answer 1

修复了这个问题，问题出在从 http.post 调用 - cold('-a-', { a: [{ attachment_token: 'token' }] }), 返回的第一个 observable 上。它没有发出新的可观察值，此时所有测试都停止了。改成of({ attachment_token: 'token' }),，测试成功

这是一个代码：

it('submit with attachment', () => {
  const response = {
    id: 'id_123',
  };
  http.post.and.returnValues(
    of({ attachment_token: 'token' }),
    cold('-a', { a: response }),
  );
  const expected = cold('-a', { a: response });

  const output = service.submit(data, attachments);

  expect(output).toBeObservable(expected);
  expect(http.post).toHaveBeenCalledTimes(2);
})

如何用 jasmine-marbles 测试 forkJoin() 运算符

How to test forkJoin() operator with jasmine-marbles

unit-testing

jasmine

rxjs

angular

jasmine-marbles