wait

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  init: function(){
    this._super();
    setTimeout(() => {
      if (!(this.isDestroyed || this.isDestroying)) {
        Ember.run(() => {
      		this.set('message', 'bar');
        });
      }
    }, 100);
  },
  message: 'foo',
});

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}}
{{my-component}}
<br>
<br>

templates.components.my-component.hbs

{{yield}} 
{{message}}
{{asyncMessage}}

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

import { moduleForComponent, test } from 'ember-qunit';
import hbs from 'htmlbars-inline-precompile';
import myComponent from '../../../components/my-component';
import wait from 'ember-test-helpers/wait';

moduleForComponent('my-component', myComponent, {
  integration: true
});

test('it renders', function(assert) {
  this.render(hbs`{{my-component}}`);
  assert.equal(this.$().text().trim(), 'foo');
  return wait().then(() => {
  	assert.equal(this.$().text().trim(), 'bar');
  });
});

tests.test-helper.js

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

setResolver(resolver);

twiddle.json

{
  "version": "0.10.6",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": true
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.9.0",
    "ember-data": "2.9.0",
    "ember-template-compiler": "2.9.0",
    "ember-testing": "2.9.0"
  },
  "addons": {}
}