New Twiddle

components.broken-render.js

import Ember from 'ember';

export default Ember.Component.extend({
  classNameBindings: ['hasInitialized:some-class'],
  rendered: 0,
  
  hasInitialized: Ember.computed('random', function() {
    return true;
  }),
  
  didRender() {
    this.rendered++;
    console.log(`rendered ${this.rendered} times`);
  },
  
  actions: {
    random() {
      this.set('random', Math.random());
    }
  }
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
<p>
  <strong>Bug:</strong> components should not be rendered when classNameBindings rely on properties that don't actually change
</p>
{{broken-render}}
<br>
<br>

templates.components.broken-render.hbs

<button {{action "random"}}>Click me</button>

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"
  }
}