Question

我正在开发一个React项目，并且正在开玩笑地为我的代码编写测试。

这是我要测试的代码。

const handleSubmit = (handleSuccess, handleErrors) => {
  signupAPI(user)
    .then(handleSuccess)
    .catch(handleErrors);
};

这是测试代码：

test('should call handleSuccess', () => {
  signupAPI.mockImplementation((user) => Promise.resolve(user));
  const handleSuccess = jest.fn();
  const handleErrors = jest.fn();

  handleSubmit(handleSuccess, handleErrors); 

  expect(signupAPI).toHaveBeenCalled(); // test passes

  expect(handleSuccess).toHaveBeenCalled(); // test fails
});

当我运行测试时，它从不会在承诺后移至“ then”部分。如何测试then部分中的函数是否实际被调用？

Answer 1

SURVEYDATE RENTALDATE OUTBOUND INBOUND VEHICLESIZE LR KR ---------- ---------- ---------- ---------- ----------- ---------- ---------- 1/24/19 2/7/19 5 5 small 855 1/24/19 2/7/19 5 5 small 455 1/24/19 2/7/19 5 5 large 851 1/24/19 2/7/19 5 5 large 451的问题在于它将promise视为荣耀的回调。无需将回调传递给handleSubmit和then。它不会返回承诺，因此无法链接。

这是可以解决的方式：

catch

和

const handleSubmit = (handleSuccess, handleErrors) => {
  return signupAPI(user)
    .then(handleSuccess)
    .catch(handleErrors);
};

这是正确编写的方式：

test('should call handleSuccess', async () => {
  ...
  handleSubmit(handleSuccess, handleErrors); 

  await handleSubmit(handleSuccess, handleErrors); 
  expect(signupAPI).toHaveBeenCalled();
  expect(handleSuccess).toHaveBeenCalled();
});

Answer 2

如果您在handleSubmit中使用退货，它将起作用。试试这个：

const handleSubmit = (handleSuccess, handleErrors) => {
  return signupAPI(user)
    .then(handleSuccess)
    .catch(handleErrors);
};

并进行测试：

test('should call handleSuccess', () => {
  signupAPI.mockImplementation((user) => Promise.resolve(user));
  const handleSuccess = jest.fn();
  const handleErrors = jest.fn();

  handleSubmit(handleSuccess, handleErrors).then(() => {
    expect(signupAPI).toHaveBeenCalled(); // test passes

    expect(handleSuccess).toHaveBeenCalled(); // test fails
  });
});

它应该可以正常工作！如果不起作用，您可以尝试在测试中为handleSubmit添加收益，例如

return handleSubmit(handleSuccess, handleErrors).then(() => {
  ...
});

Answer 3

问题是您不等待测试中创建的承诺：

test('should call handleSuccess', async() => {
  const p = Promise.resolve()
  signupAPI.mockImplementation((user) => p.then(user));
  const handleSuccess = jest.fn();
  const handleErrors = jest.fn();

  handleSubmit(handleSuccess, handleErrors); 
  await p
  expect(signupAPI).toHaveBeenCalled(); // test passes

  expect(handleSuccess).toHaveBeenCalled(); // test fails
});

如何在开玩笑之后测试随后的部分

3 个答案: