builder.rb

require_relative 'version1'
require_relative 'version2'

module Versioning
  class Builder
    class << self

      def build(version)
        version = version.to_i

        raise ArgumentError.new("Version not supported: #{version}") if version < 0 || version > 2

        return Version1.new if version == 1
        return Version2.new
      end

    end
  end
end