valid_version_format?

# File activerecord/lib/active_record/migration.rb, line 623
    def self.valid_version_format?(version_string) # :nodoc:
      [
        MigrationFilenameRegexp,
        /\A\d(_?\d)*\z/ # integer with optional underscores
      ].any? { |pattern| pattern.match?(version_string) }
    end