test(plpgsql-deparser): add schema transform demo test with fixture-based snapshots

__fixtures__/plpgsql/plpgsql_schema_rename.sql

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+-- Fixtures to test schema rename traversal
+-- These exercise complex scenarios with multiple schema references across different contexts
+
+-- Test 1: Function with schema-qualified table references in SELECT
+CREATE FUNCTION app_public.get_user_stats(p_user_id int)
+RETURNS int
+LANGUAGE plpgsql AS $$
+DECLARE
+  total_count int;
+BEGIN
+  SELECT count(*) INTO total_count
+  FROM app_public.users u
+  JOIN app_public.orders o ON o.user_id = u.id
+  WHERE u.id = p_user_id;
+  RETURN total_count;
+END$$;
+
+-- Test 2: Trigger function with INSERT into schema-qualified table
+CREATE FUNCTION app_public.audit_changes()
+RETURNS trigger
+LANGUAGE plpgsql AS $$
+BEGIN
+  INSERT INTO app_public.audit_log (table_name, operation, old_data, new_data, changed_at)
+  VALUES (TG_TABLE_NAME, TG_OP, to_json(OLD), to_json(NEW), now());
+
+  IF TG_OP = 'DELETE' THEN
+    RETURN OLD;
+  END IF;
+  RETURN NEW;
+END$$;
+
+-- Test 3: Function with UPDATE to schema-qualified table
+CREATE FUNCTION app_public.update_user_status(p_user_id int, p_status text)
+RETURNS void
+LANGUAGE plpgsql AS $$
+BEGIN
+  UPDATE app_public.users
+  SET status = p_status, updated_at = now()
+  WHERE id = p_user_id;
+
+  INSERT INTO app_public.status_history (user_id, status, changed_at)
+  VALUES (p_user_id, p_status, now());
+END$$;
+
+-- Test 4: Function with DELETE from schema-qualified table
+CREATE FUNCTION app_public.cleanup_old_sessions(p_days int)
+RETURNS int
+LANGUAGE plpgsql AS $$
+DECLARE
+  deleted_count int;
+BEGIN
+  DELETE FROM app_public.sessions
+  WHERE created_at < now() - (p_days || ' days')::interval;
+
+  GET DIAGNOSTICS deleted_count = ROW_COUNT;
+  RETURN deleted_count;
+END$$;
+
+-- Test 5: SETOF function with RETURN QUERY and schema-qualified tables
+CREATE FUNCTION app_public.get_active_orders(p_status text)
+RETURNS SETOF int
+LANGUAGE plpgsql AS $$
+BEGIN
+  RETURN QUERY
+    SELECT o.id
+    FROM app_public.orders o
+    JOIN app_public.users u ON u.id = o.user_id
+    WHERE o.status = p_status
+      AND u.is_active = true;
+  RETURN;
+END$$;
+
+-- Test 6: Function with schema-qualified function calls in expressions
+CREATE FUNCTION app_public.calculate_order_total(p_order_id int)
+RETURNS numeric
+LANGUAGE plpgsql AS $$
+DECLARE
+  subtotal numeric;
+  tax_amount numeric;
+  discount numeric;
+BEGIN
+  SELECT sum(quantity * price) INTO subtotal
+  FROM app_public.order_items
+  WHERE order_id = p_order_id;
+
+  tax_amount := app_public.get_tax_rate() * subtotal;
+  discount := app_public.get_discount(p_order_id);
+
+  RETURN subtotal + tax_amount - discount;
+END$$;
+
+-- Test 7: Function with multiple schema references in complex query
+CREATE FUNCTION app_public.get_user_dashboard(p_user_id int)
+RETURNS TABLE(metric_name text, metric_value numeric)
+LANGUAGE plpgsql AS $$
+BEGIN
+  RETURN QUERY
+    SELECT 'total_orders'::text, count(*)::numeric
+    FROM app_public.orders
+    WHERE user_id = p_user_id
+    UNION ALL
+    SELECT 'total_spent'::text, coalesce(sum(total), 0)::numeric
+    FROM app_public.orders
+    WHERE user_id = p_user_id
+    UNION ALL
+    SELECT 'active_subscriptions'::text, count(*)::numeric
+    FROM app_public.subscriptions
+    WHERE user_id = p_user_id AND status = 'active';
+  RETURN;
+END$$;
+
+-- Test 8: Trigger function with conditional logic and multiple tables
+CREATE FUNCTION app_public.sync_user_profile()
+RETURNS trigger
+LANGUAGE plpgsql AS $$
+DECLARE
+  profile_exists boolean;
+BEGIN
+  SELECT EXISTS(
+    SELECT 1 FROM app_public.profiles WHERE user_id = NEW.id
+  ) INTO profile_exists;
+
+  IF NOT profile_exists THEN
+    INSERT INTO app_public.profiles (user_id, created_at)
+    VALUES (NEW.id, now());
+  ELSE
+    UPDATE app_public.profiles
+    SET updated_at = now()
+    WHERE user_id = NEW.id;
+  END IF;
+
+  PERFORM app_public.notify_profile_change(NEW.id);
+  RETURN NEW;
+END$$;
+
+-- Test 9: Function with CTE and schema-qualified references
+CREATE FUNCTION app_public.get_top_customers(p_limit int)
+RETURNS SETOF int
+LANGUAGE plpgsql AS $$
+BEGIN
+  RETURN QUERY
+    WITH customer_totals AS (
+      SELECT user_id, sum(total) as total_spent
+      FROM app_public.orders
+      WHERE status = 'completed'
+      GROUP BY user_id
+    )
+    SELECT ct.user_id
+    FROM customer_totals ct
+    JOIN app_public.users u ON u.id = ct.user_id
+    WHERE u.is_active = true
+    ORDER BY ct.total_spent DESC
+    LIMIT p_limit;
+  RETURN;
+END$$;
+
+-- Test 10: Function with subquery in WHERE clause
+CREATE FUNCTION app_public.get_users_with_orders()
+RETURNS SETOF int
+LANGUAGE plpgsql AS $$
+BEGIN
+  RETURN QUERY
+    SELECT u.id
+    FROM app_public.users u
+    WHERE EXISTS (
+      SELECT 1 FROM app_public.orders o
+      WHERE o.user_id = u.id
+    );
+  RETURN;
+END$$;
+
+-- Test 11: Function referencing multiple schemas
+CREATE FUNCTION app_public.cross_schema_report(p_date date)
+RETURNS TABLE(source text, count bigint)
+LANGUAGE plpgsql AS $$
+BEGIN
+  RETURN QUERY
+    SELECT 'public_users'::text, count(*)
+    FROM app_public.users
+    WHERE created_at::date = p_date
+    UNION ALL
+    SELECT 'private_logs'::text, count(*)
+    FROM app_private.activity_logs
+    WHERE logged_at::date = p_date
+    UNION ALL
+    SELECT 'internal_metrics'::text, count(*)
+    FROM app_internal.metrics
+    WHERE recorded_at::date = p_date;
+  RETURN;
+END$$;
+
+-- Test 12: Procedure with schema-qualified references
+CREATE PROCEDURE app_public.process_batch(p_batch_id int)
+LANGUAGE plpgsql AS $$
+DECLARE
+  item record;
+BEGIN
+  FOR item IN
+    SELECT * FROM app_public.batch_items
+    WHERE batch_id = p_batch_id
+  LOOP
+    INSERT INTO app_public.processed_items (item_id, processed_at)
+    VALUES (item.id, now());
+
+    UPDATE app_public.batch_items
+    SET status = 'processed'
+    WHERE id = item.id;
+  END LOOP;
+
+  UPDATE app_public.batches
+  SET status = 'completed', completed_at = now()
+  WHERE id = p_batch_id;
+END$$;