Mastering React Test-Driven Development

Installing the window.fetch polyfill

For this to work in the browser, you will most likely need to install a fetch polyfill. The standard way to do this is using the whatwg-fetch packages, which you can install using the following command:

npm install --save whatwg-fetch

In src/index.js, add the following line to install a real implementation of window.fetch:

import 'whatwg-fetch';

You don't need to import this into your test modules.