title: "ReferenceError: document is not defined" when trying to test a create-react-app project
body: <p>This is my <code>__tests__/App.js</code> file:</p>
  
  <pre><code>import React from 'react';
  import ReactDOM from 'react-dom';
  import App from '../src/containers/App';
  
  it('renders without crashing', () =&gt; {
    const div = document.createElement('div');
    ReactDOM.render(&lt;App /&gt;, div);
  });
  
  // sanity check
  it('one is one', () =&gt; {
    expect(1).toEqual(1)
  });
  </code></pre>
  
  <p>And this is the output I get when running <code>yarn test</code>:</p>
  
  <pre><code>FAIL  __tests__/App.js
    ● renders without crashing
  
      ReferenceError: document is not defined
  
        at Object.&lt;anonymous&gt;.it (__tests__/App.js:6:15)
  
    ✕ renders without crashing (1ms)
    ✓ one is one
  
  Test Suites: 1 failed, 1 total
  Tests:       1 failed, 1 passed, 2 total
  Snapshots:   0 total
  Time:        0.128s, estimated 1s
  Ran all test suites related to changed files.
  </code></pre>
  
  <p>Do I need to import another module in order for <code>document</code> to be available here?</p>
  
  <p>Thanks for the help!</p>