Java Learning with
Jest https://jestjs.io/
Eloquent Java Script 3rd ed. https://eloquentjavascript.net/01_values.html
node.js
https://nodejs.org/en/docs/guides/
npm run test
https://eloquentjavascript.net/index.html
https://www.jetbrains.com/help/webstorm/running-unit-tests-on-jest.html#