reactjs - 如何使用 Jest 使用新的 React Router Hooks 模拟历史记录。

Question

我正在尝试在 react-router 上的新 useHistory Hook 内模拟 history.push 并使用 @testing-library/ react 。我只是像这里的第一个答案一样 mock 该模块:How to test components using new react router hooks?

所以我正在做:

//NotFound.js
import * as React from 'react';
import { useHistory } from 'react-router-dom';


const RouteNotFound = () => {
  const history = useHistory();
  return (
    <div>
      <button onClick={() => history.push('/help')} />
    </div>
  );
};

export default RouteNotFound;

//NotFound.test.js
describe('RouteNotFound', () => {
  it('Redirects to correct URL on click', () => {
    const mockHistoryPush = jest.fn();

    jest.mock('react-router-dom', () => ({
      ...jest.requireActual('react-router-dom'),
      useHistory: () => ({
        push: mockHistoryPush,
      }),
    }));

    const { getByRole } = render(
        <MemoryRouter>
          <RouteNotFound />
        </MemoryRouter>
    );

    fireEvent.click(getByRole('button'));
    expect(mockHistoryPush).toHaveBeenCalledWith('/help');
  });
})

但是 mockHistoryPush 没有被调用...我做错了什么？

Answer 1

在模块范围内使用jest.mock将自动提升到代码块的顶部。这样您就可以在 NotFound.jsx 文件和测试文件中获取模拟版本 react-router-dom 。

此外，我们只想模拟 useHistory 钩子(Hook)，因此我们应该使用 jest.requireActual() 来获取原始模块，并将其他方法保留为原始版本。

解决方案如下:

NotFound.jsx:

import React from 'react';
import { useHistory } from 'react-router-dom';

const RouteNotFound = () => {
  const history = useHistory();
  return (
    <div>
      <button onClick={() => history.push('/help')} />
    </div>
  );
};

export default RouteNotFound;

NotFound.test.jsx:

import React from 'react';
import { MemoryRouter } from 'react-router-dom';
import { render, fireEvent } from '@testing-library/react';
import RouteNotFound from './NotFound';

const mockHistoryPush = jest.fn();

jest.mock('react-router-dom', () => ({
  ...jest.requireActual('react-router-dom'),
  useHistory: () => ({
    push: mockHistoryPush,
  }),
}));

describe('RouteNotFound', () => {
  it('Redirects to correct URL on click', () => {
    const { getByRole } = render(
      <MemoryRouter>
        <RouteNotFound />
      </MemoryRouter>,
    );

    fireEvent.click(getByRole('button'));
    expect(mockHistoryPush).toHaveBeenCalledWith('/help');
  });
});

100%覆盖率的单元测试结果:

PASS  src/stackoverflow/58524183/NotFound.test.jsx
  RouteNotFound
    ✓ Redirects to correct URL on click (66ms)

--------------|----------|----------|----------|----------|-------------------|
File          |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
--------------|----------|----------|----------|----------|-------------------|
All files     |      100 |      100 |      100 |      100 |                   |
 NotFound.jsx |      100 |      100 |      100 |      100 |                   |
--------------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        5.133s, estimated 11s

源代码:https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/58524183