请我需要帮助，以获得这个错误的骑，我试图创建一个测试我的应用程序组件，我确保initialeTimes（）函数按预期工作，并返回下面提到的对象。
但是，当我运行测试时，它给了我以下错误：

createRoot(...): Target container is not a DOM element .import {BrowserRouter} from "react-router-dom" 
   6 |
>  7 | const root = ReactDOM.createRoot(document.getElementById('root'));
     |                       ^
   8 | root.render(
   9 |   <React.StrictMode>
  10 |     <BrowserRouter>.

字符串
下面是App.js的代码：

import {React, useReducer} from 'react';
import {Routes, Route} from "react-router-dom"
import './App.css';
import BookingPage from './components/BookingPage';
import Home from './components/Home';

function updateTimes(availableTimes, action)
{
  switch(action.type)
  {
    case 'SET_DATE':
        return {...availableTimes, select: action.payload};
    default:
      return availableTimes;
  }
}

export function  initializeTimes()
{
  return {select : null};
}

const App = ()  =>{
  const [availableTimes, dispatch] = useReducer(updateTimes, initializeTimes);

  return (
    <Routes>
        <Route path="/" element={<Home />} />
        <Route path="/booking" element={<BookingPage availableTimes={availableTimes} dispatch={dispatch} />} />
    </Routes>
  ) 
}

export default App;

型
这是测试

// App.test.js
import '@testing-library/jest-dom';
import { initializeTimes } from '../App'; 

test('initializeTimes returns the expected object', () => {
    const res = initializeTimes()
    expect(res).toEqual({ select: null });
});

型
我也试过：

// App.test.js
import '@testing-library/jest-dom';
import App, { initializeTimes } from '../App';

test('initializeTimes returns the expected object', () => {
    render(<App/>)
    const res = initializeTimes()
    expect(res).toEqual({ select: null });
});

型
我手动更新并安装了jest，但问题继续发生。我会感谢任何帮助！