Test Private Functions

testPrivateFunctions.js

var privateState = require('private-state');
var sinon = require('sinon');
var utils = require('./utils');
 
describe('utils#getDateString', function() {
  it('should print value from formatString', function() {
    var stub = sinon.stub().returns('today');
    privateState.setFunctionForTesting(utils, 'formatString', stub);
 
    var now = new Date(2015, 1, 1);
    var dateString = utils.getDateString(now);
 
    assert.equal(dateString, 'today is today');
  });
});