Jest 测试失败，因为它无法识别 props 值

Question

拥有这个 React 函数，尝试运行测试但没有通过：

import React, { useEffect } from 'react';
import { useDispatch, useSelector, shallowEqual } from 'react-redux';
import { useIntl } from 'react-intl';
import {
  PrimaryButton,
  OutlineButton
} from 'react-komodo-design';

const Buttons = () => {
  const dispatch = useDispatch();
  const intl = useIntl();

  const orderType = useSelector(
    (state) => state.orderDetails.orderDetails.orderType,
    shallowEqual
  );

 ...

  return (
    <div>
      <OutlineButton>
        {intl.formatMessage({ id: 'buttons' })}
      </OutlineButton>
      {orderType.toLowerCase() !== 't9' && (
        <PrimaryButton
          onClick={clickReorder}
        </PrimaryButton>
      )}
    </div>
  );
};

export default Buttons;

测试文件是这样的：

import React from 'react';
import { render } from '@testing-library/react';
import Buttons from './Buttons';
import { WrapIntlProvider, WrapStore } from '../../testsHelper';

describe('<Buttons />', function () {
  it('should render <Buttons></Buttons>', () => {
    const { container } = render(
      <WrapStore>
        <WrapIntlProvider>
          <Buttons />
        </WrapIntlProvider>
      </WrapStore>
    );
    expect(container).toMatchSnapshot();
  });
});

错误消息：TypeError：无法读取未定义的属性“toLowerCase”

可以做些什么来避免这个错误？

我尝试在测试函数中添加值，如下所示：

<Buttons orderType="test" /> 或 <Buttons orderType={"test'} /> 或将其作为变量发送：

describe('<Buttons />', function () {
  it('should render <Buttons></Buttons>', () => {
    const xx = "test"; // <--- added here
    const { container } = render(
      <WrapStore>
        <WrapIntlProvider>
          <Buttons orderType={xx} />
        </WrapIntlProvider>
      </WrapStore>
    );
    expect(container).toMatchSnapshot();
  });
});

Answer 1

import * as redux from 'react-redux'

const spy = jest.spyOn(redux, 'useSelector')
spy.mockReturnValue({ orderType:'test' })

尝试像这样模拟 useSelector。