New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  myService: Ember.inject.service('my-service'),
  appName: 'Ember Twiddle'
});

services.my-service.js

import Ember from 'ember';

function toggle() {
  this.toggleProperty('test');
}

export default Ember.Service.extend({
  init() {
    this._super(...arguments);
    
    this.test = false;
    this.toggleTest = toggle.bind(this);
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>
<button type='button' onclick={{action myService.toggleTest}}>Toggle Test</button>
Test: {{myService.test}}

twiddle.json

{
  "version": "0.14.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "2.18.2",
    "ember-template-compiler": "2.18.2",
    "ember-testing": "2.18.2"
  },
  "addons": {
    "ember-data": "2.18.2"
  }
}