public function testGetPersistedIncludesDates()
 {
     $vehicle = new Vehicle();
     $vehicle->setDates(['purchase_date']);
     $attributes = $vehicle->getPersistedAttributes();
     sort($attributes);
     $this->assertEquals(['color', 'created_at', 'id', 'owner_id', 'purchase_date', 'type', 'updated_at'], $attributes);
 }