test.js

import { moduleFor } from 'ember-qunit';
import test from 'mathseeds/tests/ember-sinon-qunit/test';

moduleFor('service:student-event', 'Unit | Service | student event', {
  needs: ['model:student-event']
});

test('it works', function(assert) {
  let service = this.subject();

  let _createEventSub = this.spy(service, '_createEvent');
  let resolved = new Ember.RSVP.Promise((resolve) => resolve());

  let resolvingDone = assert.async();
  service.completeActivity(1, 1, 1).returns(resolved);

  Ember.run.next( () => {
    assert.ok(_createEventSub.calledOnce, "calledONce");
    resolvingDone();
  });
});