在玩笑中检验诺言的最佳方法

Question

除非我误解了什么，否则resolves和rejects（https://facebook.github.io/jest/docs/expect.htmlet.resolves）在vNext之前都是不可用的。现在/同时，用玩笑来检验诺言的推荐方法是什么？难道这只是把期望放在那里和抓到吗？

例如:

describe('Fetching', () => {
    const filters = {
        startDate: '2015-09-01'
    };
    const api = new TestApiTransport();

    it('should reject if no startdate is given', () => {
        MyService.fetch().catch(e => expect(e).toBeTruthy()); // see rejects/resolves in v20+
    });            

    it('should return expected data', () => {
        MyService.fetch(filters, null, api).then(serviceObjects => {
            expect(serviceObjects).toHaveLength(2);
        }).catch(e => console.log(e));
    });            
});

2019年6月15号更新:在我发布这个问题后不久，Jest就开始支持这个开箱即用。我改变了下面接受的答案，以反映目前最好的方式来做到这一点。

Answer 1

我能够用AXIOS测试JEST的HTTP REST调用，就像这样。

it('has an API worth testing', async () => {
  let httpResult = null;
  await callThefunctionThatReturnsPromiseToMakeTheAxiosApiCall()
    .then(function(result) {httpResult=result;})
    .catch(function(err) {httpResult=err;});
  expect(httpResult.data.myData).toBe("myExpectedValue");
});

或

it('has an API worth testing', async () => {
  let httpResult = await callThefunctionThatReturnsPromiseToMakeTheAxiosApiCall();
  expect(httpResult.data.myData).toBe("myExpectedValue");
});

Answer 2

在 或 中返回promise和expect

describe('Fetching', () = > {
  const filters = {
    startDate: '2015-09-01'
  };
  const api = new TestApiTransport();
  it('should reject if no startdate is given', () = > {
    return MyService.fetch()
      .catch (e => expect(e).toBeTruthy()); // see rejects/resolves in v20+
  });
  it('should return expected data', () = > {
    return MyService.fetch(filters, null, api)
      .then(serviceObjects => {
        expect(serviceObjects).toHaveLength(2);
      })
  });
});

或使用

describe('Fetching', () = > {
  const filters = {
    startDate: '2015-09-01'
  };
  const api = new TestApiTransport();
  it('should reject if no startdate is given', async() = > {
    try {
      const r = await MyService.fetch()
    } catch (e) {
      expect(e).toBeTruthy()
    }
  });
  it('should return expected data', async() = > {
    const serviceObjects = await MyService.fetch(filters, null, api)
    expect(serviceObjects).toHaveLength(2);
  });
});

Answer 3

null

describe('Fetching', () => {
    const filters = {
        startDate: '2015-09-01'
    };
    const api = new TestApiTransport(); 

 it('should reject if no startdate is given', () => {
   expect.assertions(1);
   return expect(MyService.fetch()).rejects.toEqual({
     error: 'Your code message',
   });
 });          


 it('should return expected data', () => {
   expect.assertions(1);
   return expect(MyService.fetch(filters, null, api)).resolves.toEqual(extectedObjectFromApi);
 });            
});

更新(06.01.2019)

同意接受的答案不能正确工作，因为行 起到了所有的作用。链接到文档

Expect.assertions(number)验证在测试期间是否调用了一定数量的断言。在测试异步代码时，这通常很有用，可以确保回调中的断言确实被调用。

所以将这一行放在顶部将控制到测试运行时所做的断言的具体数量。