stackoverflow question#43263560-solution

controllers.application.js

import Ember from 'ember';

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

models.some-model.js

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

export default Model.extend({
  parent: belongsTo('some-model'),

  hasParent: Ember.computed('parent.id', function() {
    return Ember.isPresent(this.get('parent.id'));
  }),
});

templates.application.hbs

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

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.test-helper.js

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

setResolver(resolver);

tests.unit.models.some-model-test.js

import { moduleForModel, test } from 'ember-qunit';
import Ember from 'ember';

moduleForModel('some-model', 'Unit | Model | some-model', {});

test('hasParent', function(assert) {
  const someModel = this.subject({ id: 1, name: 'Mr. Model, Sr' });

  assert.equal(someModel.get('hasParent'), false,
    'returns false when no parent ID');

  const childModel = someModel.store.createRecord('some-model', {parent: someModel});

  assert.equal(childModel.get('hasParent'), true,
  'returns true when has parent with ID');

  childModel.set('parent', null);

  assert.equal(childModel.get('hasParent'), false,
    'returns false when no parent ID');
});

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": true
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}