New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  displayProp: Ember.computed('prop', function() {
    return `Display ${this.get('prop.number')}`;
  }),
});

components.wrapper-component.js

import Ember from 'ember';

export default Ember.Component.extend({
});

controllers.application.js

import Ember from 'ember';
//import {computed, readOnly} from 'ember-decorators'

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  prop: {number: 2},
  computedProp: Ember.computed('prop', function() {

    return `Computed ${this.get('prop.number')}`;
  }),
  
  actions: {
  	increase() {
      const number = this.get('prop.number') + 1
    	this.set('prop', {number})
    }
  }
});

templates.application.hbs

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

<button {{action (action 'increase')}}>Increase prop</button>

{{component 'my-component' prop=prop}}

<br>
<br>

{{wrapper-component 
	content=(component 'my-component' prop=prop)
}}

templates.components.my-component.hbs

<div style='border: 1px black solid'>
  <div>My component</div>
  <div>prop: {{displayProp}}</div>
</div>

templates.components.wrapper-component.hbs

<div style='border: 3px black solid'>
  wrapper component
	{{component content}}
</div>

tests.helpers.destroy-app.js

import Ember from 'ember';

export default function destroyApp(application) {
  Ember.run(application, 'destroy');
}

tests.helpers.resolver.js

import Resolver from '../../resolver';
import config from '../../config/environment';

const resolver = Resolver.create();

resolver.namespace = {
  modulePrefix: config.modulePrefix,
  podModulePrefix: config.podModulePrefix
};

export default resolver;

tests.helpers.start-app.js

import Ember from 'ember';
import Application from '../../app';
import config from '../../config/environment';

const { run } = Ember;
const assign = Ember.assign || Ember.merge;

export default function startApp(attrs) {
  let application;

  let attributes = assign({rootElement: "#test-root"}, config.APP);
  attributes = assign(attributes, attrs); // use defaults, but you can override;

  run(() => {
    application = Application.create(attributes);
    application.setupForTesting();
    application.injectTestHelpers();
  });

  return application;
}

tests.test-helper.js

import resolver from './helpers/resolver';
import {
  setResolver
} from 'ember-qunit';

setResolver(resolver);

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": true
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}