Faker\Calculator\Luhn::generateLuhnNumber PHP Method

    public static function generateLuhnNumber($partialValue)
    {
        if (!preg_match('/^\\d+$/', $partialValue)) {
            throw new InvalidArgumentException('Argument should be an integer.');
        }
        return $partialValue . Luhn::computeCheckDigit($partialValue);
    }

 /**
  * @expectedException        InvalidArgumentException
  * @expectedExceptionMessage Argument should be an integer.
  */
 public function testGenerateLuhnNumberWithInvalidPrefix()
 {
     Luhn::generateLuhnNumber('abc');
 }