validate

# File activerecord/lib/active_record/migration.rb, line 1333
      def validate(migrations)
        name, = migrations.group_by(&:name).find { |_, v| v.length > 1 }
        raise DuplicateMigrationNameError.new(name) if name

        version, = migrations.group_by(&:version).find { |_, v| v.length > 1 }
        raise DuplicateMigrationVersionError.new(version) if version
      end