我有一个我不知道如何解决的问题，运行npm test时出现此错误

永久违规：您不应<Switch>在<Router>

问题可能是什么，我该如何解决？我运行的测试是react随附的标准app.test.js

class App extends Component {
  render() {
    return (
      <div className = 'app'>
        <nav>
          <ul>
            <li><Link exact activeClassName="current" to='/'>Home</Link></li>
            <li><Link exact activeClassName="current" to='/TicTacToe'>TicTacToe</Link></li>
            <li><Link exact activeClassName="current" to='/NumGame'>Quick Maths</Link></li>
            <li><Link exact activeClassName="current" to='/HighScore'>Highscore</Link></li>
            <li><Link exact activeClassName="current" to='/Profile'>Profile</Link></li>
            <li><Link exact activeClassName="current" to='/Login'>Sign out</Link></li>
          </ul>
        </nav>
        <Switch>
          <Route exact path='/' component={Home}></Route>
          <Route path='/TicTacToe' component={TicTacToe}></Route>
          <Route path='/NumGame' component={NumberGame}></Route>
          <Route path='/HighScore' component={HighScore}></Route>
          <Route path='/Profile' component={Profile}></Route>
          <Route path='/Login' component={SignOut1}></Route>
        </Switch>
      </div>
    );
  }
};