Respect\Validation\Rules\NotOptional::validate PHP Метод

    public function validate($input)
    {
        return false === in_array($input, [null, ''], true);
    }

 /**
  * @dataProvider providerForOptional
  */
 public function testShouldNotValidateWhenOptional($input)
 {
     $rule = new NotOptional();
     $this->assertFalse($rule->validate($input));
 }