medium-create-spy.jsx

function createSpy() {
  const _renderSpy = sinon.spy();
  
  return class Spy extends Component { 
    static get lastProps() {
      return _renderSpy.args[_renderSpy.callCount - 1][0];
    }
    
    render() {
      _renderSpy(this.props);
      return <div>I am a fake component, here to spy on you!</div>;
    }
  };
}