PromiseProxyMixin UI feedback

controllers.application.js

import Ember from 'ember';
import { makeTestPromise } from '../utils/test-foo';

const TestFoo = Ember.Object.extend(Ember.PromiseProxyMixin, {
  init() {
    // By default a PromiseProxy will rethrow a
    // rejected promise causing it to be left
    // unhandled. Since by the nature of this use
    // pattern it is handled (see template) we add
    // a no-op to the end of the chain and the
    // rejection will be concidered handled.
    this.catch(() => {});
  }
});

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  actions: {
    test() {
      const promise = makeTestPromise();
      this.set('foo', TestFoo.create({promise}));
    }
  }
});

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

.info {
  color: lightblue;
}

.success {
  color: green;
}

.danger {
  color: red;
}

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<button {{action "test"}}>Click!</button>
{{#unless foo}}
  <p>Click the button to spawn a promise and see the result.</p>
{{/unless}}
{{#if foo.isPending}}
  <p class="info">Loading…</p>
{{/if}}
{{#if foo.isFulfilled}}
	<p class="success">{{foo.content}}</p>
{{/if}}
{{#if foo.isRejected}}
  <p class="danger">{{foo.reason}}</p>
{{/if}}
<p><small>Each promise has a 50/50 chance of resolving or rejecting</small></p>

twiddle.json

{
  "version": "0.8.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.5.1",
    "ember-data": "2.5.2",
    "ember-template-compiler": "2.5.1"
  }
}

utils.test-foo.js

import Ember from 'ember';

export function rand(min, max) {
  return Math.floor(Math.random() * (max - min) + min);
}

export function makeTestPromise() {
  return new Ember.RSVP.Promise((resolve, reject) => {
    const time = rand(500, 2000);
    const willResolve = rand(1, 100) % 2 === 0;
    Ember.run.later(() => {
      if (willResolve) {
        resolve('Works');
      } else {
        reject(new Error('Failed!'));
      }
    }, time);
  }, 'TestPromise');
}