如何用Promise创建Jest模拟功能？

Question

我正在尝试通过创建此Promise函数来模拟axios模块

// __mocks__/axios.js
export default function axios() {
  return new Promise((resolve) => {
    resolve({ data: {} });
  });
}

但是当我尝试在我的内部调用它时*.test.js，出现此错误

<PortalUploadForm /> › Submit Data correctly

expect(jest.fn())[.not].toHaveBeenCalledTimes()

Matcher error: received value must be a mock or spy function

Received has type:  function
Received has value: [Function axios]

Received has type:  function
    Received has value: [Function axios]

      87 |     await wait(() => {
      88 |       // mockAxios.mockResponse({ data: { ...uploadPortalResult } });
    > 89 |       expect(mockAxios).toHaveBeenCalledTimes(1);
         |                         ^
      90 |       expect(nameInput.value).toEqual(null);
      91 |     });
      92 |   });

那么，如何使用jest.fn（）制作模拟诺言函数？

谢谢！

Answer 1

在我的测试中，我通常只是像这样模拟 axios：

import axios from "axios";

jest.mock("axios");
const mockAxios = axios as jest.Mocked<typeof axios>;

然后在你的描述块中：

beforeEach(() => {
  mockAxios.request.mockImplementationOnce(
    (): Promise<any> => Promise.resolve({ hello: "world" })
  );
});

Answer 2

似乎您正在尝试将默认导出axios模拟为返回已解决的模拟函数Promise。

在这种情况下，您可以axios像这样创建模拟程序：

__mocks __ / axios.js

export default jest.fn(() => Promise.resolve({ data: {} }));

...您可以在这样的测试中使用它：

import axios from 'axios';

const func = () => axios();

test('func', async () => {
  const promise = func();
  expect(axios).toHaveBeenCalledTimes(1);  // Success!
  await expect(promise).resolves.toEqual({ data: {} });  // Success!
})