Installation

Install nvm to handle node and npm

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.5/install.sh | bash

Initialize your project’s package.json

npm init

… Add scripts and dependencies

npm pkg set 'type'='module' && npm pkg set 'scripts.test'='mocha' && npm install --save-dev mocha chai

Run the test!

npm test

Unit testing sample

Function example src/functions.js

export function helloWorld(){
  return "Hello World! xD"
}

Test example test/test.js

import assert from 'assert';
import {helloWorld} from '../src/functions.js';

describe("A simple string comparison", ()=>{
  it("String matches", ()=>{
    assert.deepEqual(helloWorld(), "Hello World! xD")
  }) 
})

Assumed project structure

myProject/
├── package.json
├── src
│   └── functions.js
└── test
    └── test.js