New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  someComputed: Ember.computed('structure.subscriptions.[]', function() {
    return 'Some Computed: ' + this.get('structure.subscriptions.firstObject.name');
  })
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  actions: {
  	doStuff(structure) {
      const sub = structure.get('subscriptions.firstObject');
      sub.set('name', 'Jon');
      sub.save();
    } 
  }
});

models.structure.js

import Model from "ember-data/model";
import attr from "ember-data/attr";
import { belongsTo, hasMany } from "ember-data/relationships";

export default Model.extend({
  subscriptions: hasMany('subscription', { async: false })
});

models.subscription.js

import Model from "ember-data/model";
import attr from "ember-data/attr";
import { belongsTo, hasMany } from "ember-data/relationships";

export default Model.extend({
  name: attr('string'),
  structure: belongsTo('structure', { async: false })
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    const subscription = this.store.createRecord('subscription', { name: 'hello' });
    return this.store.createRecord('structure', { subscriptions: [subscription] });
  },
  setupController(controller, model) {
   	controller.set('structure', model); 
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
{{structure}}
{{my-component structure=structure }}

<button {{action 'doStuff' structure }}>trigger a change</button>

templates.components.my-component.hbs

This doesn't change {{someComputed}}
<br>
<br>
But this does
{{#each structure.subscriptions as |sub|}}
  {{sub.name}}
{{/each}}

tests.helpers.destroy-app.js

import Ember from 'ember';

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

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": false
  },
  "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"
  }
}