Ember 2.10.0

components.modal.test-one.js

import Ember from 'ember';

export default Ember.Component.extend({
  isVisible: true
});

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>
<div>
	Now you see me?
	{{component 'modal.test-one'
		isVisible=true
	}}
</div>
<br>
<br>
<div>
	Now you don't! (but should)
	{{modal.test-one
		isVisible=true
	}}
</div>
<br>
<br>
<div>
	Hmm...
	{{modal/test-one
		isVisible=true
	}}
</div>

templates.components.modal.test-one.hbs

Yes

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