New Twiddle

controllers.application.js

import Ember from 'ember';

let deprecations = [];
Ember.Debug.registerDeprecationHandler((message, options, next) => {
  deprecations.pushObject(message);
  next();
});

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',

  deprecations,
  
  actions: {
    triggerDeprecation() {
       Ember.deprecate('zomg!', false, { id: 'test', until: '1.0.0' }); 
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>

<button {{action 'triggerDeprecation'}}>Trigger Deprecation</button>

<ul>
{{#each deprecations as |deprecation|}}
  <li>{{deprecation}}</li>
{{/each}}
</ul>

twiddle.json

{
  "version": "0.15.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.2.2",
    "ember-template-compiler": "3.2.2",
    "ember-testing": "3.2.2"
  },
  "addons": {
    "ember-data": "3.2.0"
  }
}