New Twiddle

application.controller.js

import Ember from 'ember';

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

application.template.hbs

<h1>{{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

helpers.format-currency.js

import Ember from 'ember';

export function helloWorld(params, hash) {
  let cents = params[0];
  let currency = hash.currency;
  return `${currency}${cents * 0.01}`;
}

export default Ember.Helper.helper(helloWorld);

index.route.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    let things = [];
    for (let i = 0; i < Math.ceil(Math.random() * 1000); i++) {
      things.push(i);
    }
    return things;
  }
});

index.template.hbs

{{#link-to 'other' id="other-link"}}Other route{{/link-to}}
<h3>Index</h3>

{{#each model as |cents|}}
	<p>{{format-currency cents currency="$"}}</p>
{{/each}}

other.route.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    let things = [];
    for (let i = 0; i < Math.ceil(Math.random() * 1000); i++) {
      things.push(i);
    }
    return things;
  }
});

other.template.hbs

<h3>Other</h3>
{{#link-to 'index' id="index-link"}}Index route{{/link-to}}
{{#each model as |cents|}}
	<p>{{format-currency cents currency="$"}}</p>
{{/each}}

router.js

import Ember from 'ember';
import config from './config/environment';

const Router = Ember.Router.extend({
  location: 'none'
});

Router.map(function() {
  this.route('other');
});

export default Router;

tests.acceptance.helper-test.js

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

moduleForAcceptance('TODO: put something here');

const RUNS = 100;

test('visiting / and /other via link clicks', function(assert) {
  assert.expect(0);
  let done = assert.async();
  visit('/');
  function repeat(count) {
    console.log("Sample: ", count);
    click('#other-link');
    click('#index-link');
    andThen(function() {
      if (count > RUNS) {
        done(); 
      } else {
        Ember.run.later(function() {
          repeat(count+1);
        }, 1001);
      }
    });
  }
  andThen(function() {
    repeat(1);
  });
});

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 startApp from '../helpers/start-app';
import destroyApp from '../helpers/destroy-app';

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

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

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

      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';

export default function startApp(attrs) {
  let application;

  let attributes = Ember.merge({rootElement: "#test-root"}, config.APP);
  attributes = Ember.merge(attributes, attrs); // use defaults, but you can override;

  Ember.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": "0.6.4",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.1/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.2/ember.prod.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.1/ember-template-compiler.js"
  }
}