This file should run, but it throws an error

jsdom-react-iframe-test.js

// Set up DOM
var jsdom = require( 'jsdom' ).jsdom;
global.document = jsdom( '' );
global.window = document.defaultView;
global.navigator = document.defaultView.navigator;

// Prepare React
var ReactTestUtils = require( 'react-addons-test-utils' );
var React = require( 'react' );

var Frame = React.createClass( {
  componentDidMount() {
    console.log( 'iframe loaded. adding content' );
    const iframe = this.refs.iframe;
    console.log( 'adding content to', iframe.contentWindow ); // Should not be null
    iframe.contentWindow.document.open();
    iframe.contentWindow.document.write( 'Hello World!' );
    iframe.contentWindow.document.close();
  },

  render() {
    console.log( 'rendering iframe' );
    return React.createElement( 'iframe', { ref: 'iframe' } );
  }
} );

// Render the component
ReactTestUtils.renderIntoDocument( React.createElement( Frame ) );