validate

# File activerecord/lib/active_record/migration.rb, line 1040
    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