New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  queryParams: [
    'nightMode'
  ],

  // NOTE: If we don't initialize the value, 
  // there's a bug
	// nightMode: true,

  // nightModeType: Ember.computed('nightMode', function() {
  //  return typeof this.get('nightMode');
  // })
});

templates.application.hbs

<style>
	.night-mode {
    background-color: black;
    color: white;
  }
</style>
<div 
	class="{{if nightMode "night-mode"}}"
  style="height: 100vh; width: 100vw;"
>
  <h1>
    Debugging Ember Code!!
  </h1>
  
  <label for="nightModeToggle">
    toggle night mode 
  </label>
  
  <input 
    id="nightModeToggle"
    value={{nightMode}} 
    onClick={{toggle "nightMode" this}}
    type="checkbox" 
  />
  
  <br>
  {{nightModeType}}
</div>

tests.acceptance.night-mode-test.js

import { test } from 'qunit';
import moduleForAcceptance from '../../tests/helpers/module-for-acceptance';

moduleForAcceptance('Night Mode');

test('Night mode works', function(assert) {
  visit('/');

  andThen(function() {
    assert.equal(
      find('div').hasClass('night-mode'), 
      false
    );
  });
  
	click('input');
  
  andThen(function() {
    assert.equal(
      find('div').hasClass('night-mode'), 
      true
    );
  });
  
	click('input');
  andThen(function() {
    assert.equal(
      find('div').hasClass('night-mode'), 
      false 
    );
  });
});

tests.helpers.destroy-app.js

import Ember from 'ember';

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

tests.helpers.module-for-acceptance.js

import { module } from 'qunit';
import Ember from 'ember';
import startApp from '../helpers/start-app';
import destroyApp from '../helpers/destroy-app';

const { RSVP: { Promise } } = Ember;

export default function(name, options = {}) {
  module(name, {
    beforeEach() {
      this.application = startApp();

      if (options.beforeEach) {
        return options.beforeEach.apply(this, arguments);
      }
    },

    afterEach() {
      let afterEach = options.afterEach && options.afterEach.apply(this, arguments);
      return Promise.resolve(afterEach).then(() => destroyApp(this.application));
    }
  });
}

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",
    "ember-composable-helpers": "1.0.0"
  }
}