title: Error when running npm test
body: <p>I'm new to testing in React and so I'm trying to implement some tests for an application I've already been working on.</p>
  
  <p>I run npm test and I get this error:</p>
  
  <p><a href="https://i.stack.imgur.com/LNIEB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LNIEB.png" alt="enter image description here"></a></p>
  
  <p>Here's the default test in file <code>App.test.js</code>:</p>
  
  <pre><code>import React from 'react';
  import ReactDOM from 'react-dom';
  
  import App from './App';
  
  it('renders without crashing', () =&gt; {
    const div = document.createElement('div');
    ReactDOM.render(&lt;App /&gt;, div);
    ReactDOM.unmountComponentAtNode(div);
  });
  </code></pre>