http://jsfiddle.net/Brj8m/

onClick.mockClear();
    ReactTestUtils.Simulate.click(ReactDOM.findDOMNode(button));
    expect(onClick.mock.calls.length).toBe(0);
  }
  function mounted(button) {
    button = ReactTestUtils.renderIntoDocument(button);
    return button;
  }
  beforeEach(function() {
    React = require('React');
    ReactDOM = require('ReactDOM');
    ReactTestUtils = require('ReactTestUtils');
  });
  it('should forward clicks when it starts out not disabled', function() {
    expectClickThru(mounted(<button onClick={onClick} />));
  });
  it('should not forward clicks when it starts out disabled', function() {
    expectNoClickThru(
      mounted(<button disabled={true} onClick={onClick} />)
    );
  });
  it('should forward clicks when it becomes not disabled', function() {
    var container = document.createElement('div');
    var btn = ReactDOM.render(
      <button disabled={true} onClick={onClick} />,
      container
    );
    btn = ReactDOM.render(
      <button onClick={onClick} />,