# frozen_string_literal: true class IsbnValidator < BaseValidator CHARACTERS = %w[ 0 1 2 3 4 5 6 7 8 9 x ].freeze private def valid_attr? values = value.to_s.gsub(/-| /, "").downcase.chars [10, 13].include?(values.size) && values.all? { |chr| CHARACTERS.include?(chr) } end end