Enzyme is a React Testing utility written by the developers at Airbnb that is designed to make testing your components much simpler and easier.

Here’s a quick tip for testing onClick functions where your code calls event.preventDefault()

When triggering a click via the Enzyme api method simulate, you are not actually triggering a real event – the underlying implementation is simply calling the onClick prop of the node.

So if you’re calling event.preventDefault() in your code, you will need to pass a second argument to simulate, which is a mock object, that is passed through to the event handler.

For example:

1
2

const wrapper = shallow(<YourComponent />);
wrapper.find('a').simulate('click', { preventDefault() {} });

Easy when you know how, but not immediately obvious. Fortunately the Enzyme docs are brilliant and well worth checking out for further detail and examples.