Extract generic rename_constraint helper

To be used for PK conversion.

Related to https://gitlab.com/gitlab-org/gitlab/-/issues/288005.

db/post_migrate/20210622041846_finalize_push_event_payloads_bigint_conversion.rb

@@ -46,11 +46,11 @@ class FinalizePushEventPayloadsBigintConversion < ActiveRecord::Migration[6.1]
       # Drop FK fk_36c74129da
       remove_foreign_key TABLE_NAME, name: concurrent_foreign_key_name(TABLE_NAME, :event_id)
       # Change the name of the FK for event_id_convert_to_bigint to the FK name for event_id
-      execute <<~SQL
-          ALTER TABLE #{TABLE_NAME}
-          RENAME CONSTRAINT #{concurrent_foreign_key_name(TABLE_NAME, :event_id_convert_to_bigint)}
-          TO #{concurrent_foreign_key_name(TABLE_NAME, :event_id)}
-      SQL
+      rename_constraint(
+        TABLE_NAME,
+        concurrent_foreign_key_name(TABLE_NAME, :event_id_convert_to_bigint),
+        concurrent_foreign_key_name(TABLE_NAME, :event_id)
+      )
     end
   end
 end

lib/gitlab/database/migration_helpers.rb

@@ -1627,6 +1627,13 @@ into similar problems in the future (e.g. when new tables are created).
         execute "ALTER TABLE #{quote_table_name(table_name)} RENAME COLUMN #{quote_column_name(temp_name)} TO #{quote_column_name(column_2)}"
       end
 
+      def rename_constraint(table_name, old_name, new_name)
+        execute <<~SQL
+          ALTER TABLE #{quote_table_name(table_name)}
+          RENAME CONSTRAINT #{quote_column_name(old_name)} TO #{quote_column_name(new_name)}
+        SQL
+      end
+
       private
 
       def validate_check_constraint_name!(constraint_name)

rubocop/cop/migration/with_lock_retries_disallowed_method.rb

@@ -22,6 +22,7 @@ module RuboCop
           remove_foreign_key_if_exists
           remove_foreign_key_without_error
           rename_index
+          rename_constraint
           table_exists?
           index_exists_by_name?
           foreign_key_exists?

spec/lib/gitlab/database/migration_helpers_spec.rb

@@ -3027,4 +3027,12 @@ RSpec.describe Gitlab::Database::MigrationHelpers do
         .to raise_error 'Cannot call swap_column_names without a transaction open or outside of a transaction block.'
     end
   end
+
+  describe '#rename_constraint' do
+    it "executes the statement to rename constraint" do
+      expect(model).to receive(:execute).with /ALTER TABLE "test_table"\nRENAME CONSTRAINT "fk_old_name" TO "fk_new_name"/
+
+      model.rename_constraint(:test_table, :fk_old_name, :fk_new_name)
+    end
+  end
 end