Test a Render Prop!

the-light.jsx

describe('when <App /> renders', () => {
  const wrapper = shallow(<App />)
    .find(Mouse)
    .renderProp('render', { x: 0, y: 0 });

  it('should render a headline containing the coordinates', () => {
    expect(wrapper.equals(<h1>The mouse position is (0, 0)</h1>)).toBe(true);
  });
});