Test Double : Dummy Object (Javascript)

test_double_spy_1.js

//the real world implementation
function Alerter(){
  this.alert = (msg){
     window.alert(msg);
  };
}
 
var Alerter = new Alerter();

//the Alerter is injected into here
angular.module('app').controller(function(Alerter){
 
     Alerter.alert('hello world');
 
});