`SyntheticEvent.type` is undefined when received by the handler. Or the nativeEvent type for that matter.

Needs to be added in here somewhere: https://github.com/facebook/react/blob/3a4e1dbb5b2957875cab6af11a5e5934e125a0d8/src/test/ReactTestUtils.js#L496

I realize that it's not sustainable to have to set _all_ the possible fields for a simulated event, but the type at least makes sense for verification that you're getting the right _sort_ of event.

'ReactShallowRenderer render(): Invalid component element. Instead of ' +
      'passing a component class, make sure to instantiate it by passing it ' +
      'to React.createElement.'
    );
    expect(() => shallowRenderer.render(<div />)).toThrowError(
      'ReactShallowRenderer render(): Shallow rendering works only with ' +
      'custom components, not primitives (div). Instead of calling ' +
      '`.render(el)` and inspecting the rendered output, look at `el.props` ' +
      'directly instead.'
    );
  });
  it('should have shallow unmounting', function() {
    var componentWillUnmount = jest.fn();
    var SomeComponent = React.createClass({
      render: function() {
        return <div />;
      },
      componentWillUnmount,
    });
    var shallowRenderer = ReactTestUtils.createRenderer();
    shallowRenderer.render(<SomeComponent />);
    shallowRenderer.unmount();
    expect(componentWillUnmount).toBeCalled();
  });
  it('can shallow render to null', function() {
    var SomeComponent = React.createClass({
      render: function() {
        return null;
      },
    });