Example of unit test issues in AMD

amd.js

define([
  'app/viewModels/user'
], function(User) {
  var SomeViewModel = function() {
    this.users = [];
    this.addUser();
  };
  
  SomeViewModel.prototype.addUser = function() {
    // Sometimes I wan't to fake this `User` or whatever. It's hard to do w/ AMD.
    this.users.push(new User());
  };
});