text: /**
   * Copyright (c) 2013-present, Facebook, Inc.
   *
   * This source code is licensed under the MIT license found in the
   * LICENSE file in the root directory of this source tree.
   *
   * @emails react-core
   */
  
  'use strict';
  
  let React = require('react');
  const ReactTestUtils = require('react-dom/test-utils');
  
  class TextWithStringRef extends React.Component {
    render() {
      jest.resetModules();
      React = require('react');
      return <span ref="foo">Hello world!</span>;
    }
  }
  
  describe('when different React version is used with string ref', () => {
    it('throws the "Refs must have owner" warning', () => {
      expect(() => {
        ReactTestUtils.renderIntoDocument(<TextWithStringRef />);
      }).toThrow(
        'Element ref was specified as a string (foo) but no owner was set. This could happen for one of' +
          ' the following reasons:\n' +
          '1. You may be adding a ref to a functional component\n' +
          "2. You may be adding a ref to a component that was not created inside a component's render method\n" +
          '3. You have multiple copies of React loaded\n' +
          'See https://fb.me/react-refs-must-have-owner for more information.',
      );
    });
  });
  