Unit test the JavaScript code with Mocha

Introduction

Install required libraries with npm

• esm@3.2.25
• chai@4.3.4
• mocha@8.3.2

$ npm install -g esm@3.2.25 chai@4.3.4 mocha@8.3.2

and use mocha to do unittest (in the same directory with .mocharc.js)

$ mocha