First, let's add a new command to the scripts field of our package.json file:
"test": "mocha --exit test/ --require babel-hook --require @babel/polyfill --recursive"
If you now execute npm run test, we'll run the mocha package in the test folder, which we'll create in a second. The preceding --require option loads the specified file or package. We'll also load a babel-hook.js file, which we'll create as well. The --recursive parameter tells Mocha to run through the complete file tree of the test folder, not just the first layer. This behavior is useful because it allows us to structure our tests in multiple files and folders.
Let's begin with the babel-hook.js file by adding it to the root of our project, next to the ...
