Testing relationships in tests

controllers.application.js

import Ember from 'ember';

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

models.child.js

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

export default Model.extend({
  parent: belongsTo('parent'),
  name: attr('string'),
  isGood: attr('bool'),
});

models.parent.js

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

const { computed } = Ember;

export default Model.extend({
  children: hasMany('child', { async: true }),
  
  goodChildren: computed('children.@each.isGood', function() {
    return this.get('children')
      .filter(ch => !!ch.get('isGood'))
    	.sort((ch1, ch2) => ch1.get('name') > ch2.get('name'));
  }),
});

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.parent-test.js

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

moduleForModel('parent', 'Unit | Model | parent', {
  needs: ['model:child']
});

test('it has good children', function(assert) {
  let parent = this.subject();
  
  assert.equal(parent.get('children.length'), 0, 'has no children');

  parent.store.createRecord('child', { parent });
  
  assert.equal(parent.get('children.length'), 1, 'has a child');
  assert.equal(parent.get('goodChildren.length'), 0, 'does not have good children');

  parent.store.createRecord('child', { parent, isGood: true });
  
  assert.equal(parent.get('children.length'), 2, 'has two children');
  assert.equal(parent.get('goodChildren.length'), 1, 'has 1 good child');
});

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": "1.13.13",
    "ember-template-compiler": "1.13.13",
    "ember-testing": "1.13.13"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}