New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  test: "False"
});

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>
{{outlet}}
<br>
<br>

templates.components.my-component.hbs

{{input type="text" focus-out=(action (mut test) "True") }}
<p data-test-p >{{test}}</p>

tests.integration.components.my-component-test.js

import { moduleForComponent, test } from 'ember-qunit';
import hbs from 'htmlbars-inline-precompile';
import {blur} from 'ember-test-helpers';

moduleForComponent('my-component', 'TODO: put something here', {
  integration: true
});

test('it renders', async function(assert) {
  await this.render(hbs`{{my-component}}`);
  assert.equal(this._element.querySelector('[data-test-p]').textContent, "False")
  await blur(this._element.querySelector('input'))
  assert.equal(this._element.querySelector('[data-test-p]').textContent, "True")
});

tests.test-helper.js

import Application from '../app';
import config from '../config/environment';
import { setApplication } from '@ember/test-helpers';
import { start } from 'ember-qunit';
import { assign } from '@ember/polyfills';

let attributes = assign({ rootElement: '#main' }, config.APP);
setApplication(Application.create(attributes));

start();

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": true
  },
  "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"
  }
}