IsoCodes\Grai::validate PHP Method

    public static function validate($grai)
    {
        if (strlen($grai) < 13) {
            return false;
        }
        $grai = self::unDecorate($grai);
        if (0 !== (int) $grai[0]) {
            return false;
        }
        $grai = substr($grai, 1, strlen($grai) - 1);
        if (strlen($grai) > 29) {
            return false;
        }
        $gtin13 = substr($grai, 0, 13);
        return parent::check($gtin13, 13);
        // optional serial component not to be checked
    }

 /**
  * testInvalidGrai
  *
  * @param mixed $grai
  *
  * @dataProvider getInvalidGrai
  *
  * @return void
  */
 public function testInvalidGrai($grai)
 {
     $this->assertFalse(Grai::validate($grai));
 }