test.js

var assert = require('assert');
var expect = require('expect.js');
var add = require('../add');

describe('add',function() {
    it('should expose a function', function() {
		expect(add).to.be.a('function');
	});
    it ('should add the values', function() {
		expect(add(1,3)).to.equal(4);
    });
});