An example of a simple unit test written with Mocha and expect.js.

lazy-dev2-example1.js

var expect = require("expect.js");

describe('A simple unit test', function () {
    it('should add two integers and return the sum', function () {

        // implementation to go here

        expect(add(3, 9)).to.be(12);
        expect(add('a', 8)).to.not.be.a('number');
        expect(add.length).to.be(2);
    });
});