fizzbuzz.js

module.exports = (function() {

  var fizzFun = function(n){
    if (n % 3 == 0)
      return 'fizz';
  };

  var buzzFun = function(n){
    if (n % 5 == 0)
      return 'buzz';
  };

  var funs = [fizzFun, buzzFun];

  var FizzBuzz = function() { };

  FizzBuzz.prototype.process = function(n) {

	  var result = funs.map(function(f){
	    return f(n) || '';  
	  }).reduce(function(p, c){
	    return p + c;
	  });
	  
	  if (result == '')
	    return n;
	  return result;
	};

return FizzBuzz;

})();

fizzbuzz_spec.js

var	sinon = require("sinon")
var FizzBuzz = require("../libs/fizzBuzz");
var should = require("should")

describe("FizzBuzz", function() {

	beforeEach(function() {
		this.fizzBuzz = new FizzBuzz();
	});

	it("1 should return 1", function() {
		var result = this.fizzBuzz.process(1);
		result.should.eql(1);
	});

	it("2 should return 2", function() {
		var result = this.fizzBuzz.process(2);
		result.should.eql(2);
	});

	it("3 should return fizz", function() {
		var result = this.fizzBuzz.process(3);
		result.should.eql('fizz');
	});

	it("6 should return fizz", function() {
		var result = this.fizzBuzz.process(6);
		result.should.eql('fizz');
	});

	it("5 should return buzz", function() {
		var result = this.fizzBuzz.process(5);
		result.should.eql('buzz');
	});

	it("15 should return fizzbuzz", function() {
		var result = this.fizzBuzz.process(15);
		result.should.eql('fizzbuzz');
	});
});