Could not find the "presence" validator with Ember Validations addon

I'm trying to use the Ember Validations addon and I can't get it working. In the Chrome console, I see: WARNING: Could not find the "presence" validator.

Here is my model:

import Ember from 'ember';
import DS from 'ember-data';
import EmberValidations from 'ember-validations';

export default DS.Model.extend(EmberValidations.Mixin, {
  name: DS.attr('string'),

  validations: {
    name: {
      presence: true
    }
  }
});

And here is the my test:

test('isValid is false if name is not set', function(assert) {
  stop();
  var model = this.subject();
  Ember.run(function() {
    model.validate().then(function() {
      assert.equal(model.get('isValid'), false);
      start();
    });
  });
});

The result of this test is "expected false but got true". Thanks in advance!