Test reads propery

components.sample-component.js

import Component from '@ember/component';
import { readOnly, reads } from '@ember/object/computed';

export default Component.extend({
  newProperty: readOnly('test'),
  sameProperty: reads('test'),
  actions: {
    increment(value) {
      value = value + 1;
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

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

{{sample-component test=1}}
<br>
<br>
{{outlet}}
<br>
<br>

templates.components.sample-component.hbs

<button {{action 'increment' newProperty}}>
	{{newProperty}} +
</button>
<br>
{{sameProperty}}

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}