React 0.14.7: `<option value="">empty</option>` emits empty string on change
http://jsbin.com/pisita/10/edit?html,js,console,output
React 15.0.0-rc.1`<option value="">empty</option>` emits string with value "empty" on change
http://jsbin.com/bemaze/12/edit?html,js,console,output
This is because React 15.0.0-rc.1 cuts off `value=""` from option tag

'both). Decide between using a controlled or uncontrolled input ' +
      'element and remove one of these props. More info: ' +
      'https://fb.me/react-controlled-components'
    );
    ReactTestUtils.renderIntoDocument(
      <input type="radio" checked={true} defaultChecked={true} readOnly={true} />
    );
    expect(console.error.argsForCall.length).toBe(1);
  });
  it('should warn if value and defaultValue props are specified', function() {
    ReactTestUtils.renderIntoDocument(
      <input type="text" value="foo" defaultValue="bar" readOnly={true} />
    );
    expect(console.error.argsForCall[0][0]).toContain(
      'A component contains an input of type text with both value and defaultValue props. ' +
      'Input elements must be either controlled or uncontrolled ' +
      '(specify either the value prop, or the defaultValue prop, but not ' +
      'both). Decide between using a controlled or uncontrolled input ' +
      'element and remove one of these props. More info: ' +
      'https://fb.me/react-controlled-components'
    );
    ReactTestUtils.renderIntoDocument(
      <input type="text" value="foo" defaultValue="bar" readOnly={true} />
    );
    expect(console.error.argsForCall.length).toBe(1);
  });
  it('should warn if controlled input switches to uncontrolled', function() {
    var stub = <input type="text" value="controlled" onChange={emptyFunction} />;
    var container = document.createElement('div');
    ReactDOM.render(stub, container);