How do we unit test a Model Mixin with ember-cli

I have few Ember.Mixin in my app that contains DS.attr() and / or DS.belongsTo(). I was wondering how should I unit test them ?

By default, ember-cli generate this test

test('it works', function(assert) {
  var MyModelObject = Ember.Object.extend(MyModelMixin);
  var subject = MyModelObject.create();
  assert.ok(subject);
});

But when I tried to interact with an DS.attr() I got the following error:

TypeError: Cannot read property '_attributes' of undefined
  at hasValue (http://localhost:4200/assets/vendor.js:90650:25)
  at Class.get (http://localhost:4200/assets/vendor.js:90730:13)
  at Descriptor.ComputedPropertyPrototype.get (http://localhost:4200/assets/vendor.js:29706:28)
  at Object.get (http://localhost:4200/assets/vendor.js:35358:19)
  at Class.get (http://localhost:4200/assets/vendor.js:49734:38)
  at Object.<anonymous> (http://localhost:4200/assets/tests.js:20126:25)
  at runTest (http://localhost:4200/assets/test-support.js:2779:28)
  at Object.run (http://localhost:4200/assets/test-support.js:2764:4)
  at http://localhost:4200/assets/test-support.js:2906:11
  at process (http://localhost:4200/assets/test-support.js:2565:24)

Which make senses. What is the best way to do it ? Should I create a DS.Model within the test and then apply the mixin on it ?

Thanks !