New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  getValue(){
    var a = 7 * 2;
    return a;
  },

  getResult(){
    var result = this.getValue(); // result is not function 
    return `Test ${result}`;
  },
  actions: {
    test() {
      alert(this.getResult());
    }
  }
});

templates.application.hbs

<button onclick={{action 'test'}}>Test</button>

twiddle.json

{
  "version": "0.13.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.16.2",
    "ember-template-compiler": "2.16.2",
    "ember-testing": "2.16.2"
  },
  "addons": {
    "ember-data": "2.16.3"
  }
}