Getting tests to run with React

Is there a sort of general, step-by-step guide on how to get tests to run with React projects. I don’t mind if it involves Codepen or GitHub, but I am flummoxed.

On Codepen you can just add the test script to the JS section (Settings > JS).

On CodeSandbox you have to use the “External resource” section (below the dependencies).

In a create-react-app you can add the script using a script element at the end of the HTML file in the public folder (just before the closing body tag) just like you would with a plain HTML/JS site.