.babelrc

{
  "presets": [
     "react",
     "es2015"
  ]
}

jest output.txt

● Runtime Error
SyntaxError: Unexpected token <
    at eval (native)
    at Object.<anonymous> (/Users/sawyer/Sites/Siteleaf/app/assets/js/main-component.jsx:3:23)
    at Object.<anonymous> (/Users/sawyer/Sites/Siteleaf/app/assets/js/__tests__/main-component-test.js:4:21)
    at emitTwo (events.js:87:13)
    at process.emit (events.js:172:7)
    at handleMessage (internal/child_process.js:686:10)
    at Pipe.channel.onread (internal/child_process.js:440:11)

main-component-test.js

'use strict';

jest.dontMock('../main-component');
var MainComponent = require('../main-component');

describe('Metadata String Field', () => {
  it('should include nested component', () => {
    // Dummy test to just get things working...
    expect(true).toBe(true);
  });
});

main-component.jsx

"use strict";
var React = require('react');
var NestedComponent = require('app-js/nested-component');

var MainComponent = React.createClass({
  render() {
    return (
      <div>
        <NestedComponent />
        <textarea />
      </div>
    )
  }
});

module.exports = MainComponent;

nested-component.jsx

"use strict";
var React = require('react');

var NestedComponent = React.createClass({
  render() {
    return (
      <div>
        <strong>Hello world</strong>
      </div>
    )
  }
});

module.exports = NestedComponent;