public function testMultipleFieldsWithNull()
{
$this->specify('Test uniqueness with combination of fields and a null value.', function () {
$validation = new Validation();
$validation->add(['type', 'deleted'], new Uniqueness());
$messages = $validation->validate(null, $this->robot);
expect($messages->count())->equals(1);
$messages = $validation->validate(null, $this->anotherRobot);
expect($messages->count())->equals(0);
$messages = $validation->validate(null, $this->deletedRobot);
expect($messages->count())->equals(0);
});
}