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

it('should warn if value is null', function() {
    spyOn(console, 'error');
    ReactTestUtils.renderIntoDocument(<textarea value={null} />);
    expect(console.error.argsForCall[0][0]).toContain(
      '`value` prop on `textarea` should not be null. ' +
      'Consider using the empty string to clear the component or `undefined` ' +
      'for uncontrolled components.'
    );
    ReactTestUtils.renderIntoDocument(<textarea value={null} />);
    expect(console.error.argsForCall.length).toBe(1);
  });
  it('should warn if value and defaultValue are specified', function() {
    spyOn(console, 'error');
    ReactTestUtils.renderIntoDocument(
      <textarea value="foo" defaultValue="bar" readOnly={true} />
    );
    expect(console.error.argsForCall[0][0]).toContain(
      'Textarea 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 textarea ' +
      'and remove one of these props. More info: ' +
      'https://fb.me/react-controlled-components'
    );
    ReactTestUtils.renderIntoDocument(
      <textarea value="foo" defaultValue="bar" readOnly={true} />
    );
    expect(console.error.argsForCall.length).toBe(1);
  });
});