Testing route with unauthenticatedRouteMixin fails with "Promise rejected before it exists"

THE ROUTE

import Ember from "ember";
import UnauthenticatedRouteMixin from 'ember-simple-auth/mixins/unauthenticated-route-mixin';

const {
  Route,
} = Ember;​

export default Route.extend(UnauthenticatedRouteMixin, {

});

THE TEST

import { moduleFor, test } from 'ember-qunit';​

moduleFor('route:index', 'Unit | Route | index', {});

test('it exists', function(assert) {
  var route = this.subject();
  assert.ok(route);
});

THE ERROR

Promise rejected before it exists: Could not find module `ember-simple-auth/mixins/unauthenticated-route-mixin` imported from `appname/routes/index`

Ember: 1.13.15

Ember Simple Auth: 1.0.1

It is just the standard test generated by ember but fails everytime.

Thank you for any help