index.js

module.exports = (function () {
	var constructor = function (timer) {
		console.log('hi');
		timer.Start();
		return 666;
	}

	return constructor;
})();

test.js

var assert = require("assert")
var sinon = require('sinon');

var mmsProcessor = require('../MMS/MMSProcessor.js');

describe('MMSProcessor', function(){
  describe('DownloadFiles', function(){
  	
    it('should start timer', function(){

 	    var myAPI = { Start: function () {} };

 	    var mock = sinon.mock(myAPI);
      mock.expects("Start").once();
	    mmsProcessor(mock);
      mock.verify();

    })
  })
})

// when i runt the test i get  TypeError: Object #<Object> has no method 'Start'