Test a Render Prop!

render-prop-test.jsx

import { shallow } from 'enzyme'

describe('when the mouse moves', () => {
  const renderMock = jest.fn();
  const wrapper = shallow(<Mouse render={renderMock} />);
  wrapper.find('div').simulate('mousemove', {
    clientX: 50,
    clientY: 20,
  });

  it('should call `render` with the mouse coordinates', () => {
    expect(renderMock).toHaveBeenCalledWith({ x: 50, y: 20 });
  });
});