test(pg): cover stale cloudsync_table_settings + dropped meta-table reopen

Mirrors the SQLite unit test do_test_stale_table_settings_dropped_meta.
Drops the base table and its <table>_cloudsync meta-table without
calling cloudsync_cleanup, reconnects to force a fresh backend, and
verifies that cloudsync_init on a new table still succeeds. Before the
shared fix in cloudsync_dbversion_rebuild this aborted with
"An error occurred while trying to initialize context" because
SQL_DBVERSION_BUILD_QUERY's string_agg over zero rows produced a NULL
SQL string that was misreported as DBRES_NOMEM.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: andinux

test/postgresql/51_stale_table_settings_dropped_meta.sql

@@ -0,0 +1,123 @@
+-- 'Stale cloudsync_table_settings with dropped meta-table'
+-- Mirrors the SQLite unit test: Stale Table Settings Dropped Meta
+--
+-- When a user drops a tracked table and its <table>_cloudsync meta-table
+-- manually (without calling cloudsync_cleanup), cloudsync_table_settings is
+-- left with stale rows while pg_tables no longer has any matching
+-- *_cloudsync table. Before the fix in cloudsync_dbversion_rebuild, opening a
+-- new backend and calling any cloudsync function caused
+-- cloudsync_dbversion_build_query to produce a NULL SQL string (string_agg
+-- over zero rows), which was misreported as DBRES_NOMEM, making
+-- cloudsync_context_init fail and every cloudsync_* call ereport ERROR.
+
+\set testid '51'
+\ir helper_test_init.sql
+
+\connect postgres
+\ir helper_psql_conn_setup.sql
+
+DROP DATABASE IF EXISTS cloudsync_test_51;
+CREATE DATABASE cloudsync_test_51;
+
+\connect cloudsync_test_51
+\ir helper_psql_conn_setup.sql
+
+CREATE EXTENSION IF NOT EXISTS cloudsync;
+
+-- Phase 1: create a tracked table and initialize cloudsync on it.
+DROP TABLE IF EXISTS stale_doc CASCADE;
+CREATE TABLE stale_doc (id TEXT PRIMARY KEY NOT NULL, body TEXT);
+SELECT cloudsync_init('stale_doc', 'CLS', 1) AS _init \gset
+
+-- Sanity: the meta-table exists and cloudsync_table_settings has a row for it.
+SELECT count(*) AS meta_exists FROM pg_tables WHERE tablename = 'stale_doc_cloudsync' \gset
+SELECT (:meta_exists::int = 1) AS meta_exists_ok \gset
+\if :meta_exists_ok
+\echo [PASS] (:testid) stale_doc_cloudsync meta-table created
+\else
+\echo [FAIL] (:testid) expected stale_doc_cloudsync to exist
+SELECT (:fail::int + 1) AS fail \gset
+\endif
+
+SELECT count(*) AS settings_rows FROM cloudsync_table_settings WHERE tbl_name = 'stale_doc' \gset
+SELECT (:settings_rows::int > 0) AS settings_rows_ok \gset
+\if :settings_rows_ok
+\echo [PASS] (:testid) cloudsync_table_settings has row(s) for stale_doc
+\else
+\echo [FAIL] (:testid) expected cloudsync_table_settings row for stale_doc
+SELECT (:fail::int + 1) AS fail \gset
+\endif
+
+-- Phase 2: drop BOTH the base table and the meta-table without calling
+-- cloudsync_cleanup. cloudsync_table_settings still references stale_doc,
+-- but pg_tables has no *_cloudsync tables at all now.
+DROP TABLE stale_doc;
+DROP TABLE stale_doc_cloudsync;
+
+SELECT count(*) AS cloudsync_meta_tables FROM pg_tables WHERE tablename LIKE '%_cloudsync' \gset
+SELECT (:cloudsync_meta_tables::int = 0) AS no_meta_ok \gset
+\if :no_meta_ok
+\echo [PASS] (:testid) no *_cloudsync meta-tables remain in pg_tables
+\else
+\echo [FAIL] (:testid) expected zero *_cloudsync tables, got :cloudsync_meta_tables
+SELECT (:fail::int + 1) AS fail \gset
+\endif
+
+-- Phase 3: reconnect to force a fresh backend. pg_cloudsync_context is a
+-- static per-process pointer, so a new backend means
+-- cloudsync_pg_context_init runs again on the next cloudsync call — which
+-- is exactly what used to fail under this bug.
+\connect cloudsync_test_51
+\ir helper_psql_conn_setup.sql
+
+-- cloudsync_version is a pure function that does not touch the context, so
+-- this call cannot fail even with the bug present. It's here only as a
+-- trivial smoke check that the extension is still loadable.
+SELECT cloudsync_version() IS NOT NULL AS version_ok \gset
+\if :version_ok
+\echo [PASS] (:testid) cloudsync_version() reachable after reopen
+\else
+\echo [FAIL] (:testid) cloudsync_version() failed after reopen
+SELECT (:fail::int + 1) AS fail \gset
+\endif
+
+-- The real check: calling a function that goes through get_cloudsync_context()
+-- must succeed. Before the fix, cloudsync_dbversion_rebuild returned
+-- DBRES_NOMEM here because SQL_DBVERSION_BUILD_QUERY's string_agg over zero
+-- rows produced a NULL SQL string, and the whole init path would ereport
+-- ERROR — any cloudsync_* call below would abort the script.
+CREATE TABLE stale_doc2 (id TEXT PRIMARY KEY NOT NULL, body TEXT);
+SELECT cloudsync_init('stale_doc2', 'CLS', 1) AS _init2 \gset
+
+-- The new table's meta-table exists. If cloudsync_init failed (pre-fix
+-- behavior) this count will be 0, covering both the init-rc check and the
+-- meta-table creation in a single assertion.
+SELECT count(*) AS meta2_exists FROM pg_tables WHERE tablename = 'stale_doc2_cloudsync' \gset
+SELECT (:meta2_exists::int = 1) AS meta2_exists_ok \gset
+\if :meta2_exists_ok
+\echo [PASS] (:testid) cloudsync_init succeeded and stale_doc2_cloudsync was created
+\else
+\echo [FAIL] (:testid) expected stale_doc2_cloudsync to exist after cloudsync_init
+SELECT (:fail::int + 1) AS fail \gset
+\endif
+
+-- An insert via the new cloudsync_init'd table should produce a cloudsync
+-- metadata entry — confirming the context is fully functional.
+INSERT INTO stale_doc2 (id, body) VALUES ('a', 'hello');
+
+SELECT count(*) AS meta_rows FROM stale_doc2_cloudsync \gset
+SELECT (:meta_rows::int > 0) AS meta_rows_ok \gset
+\if :meta_rows_ok
+\echo [PASS] (:testid) stale_doc2_cloudsync has metadata after insert
+\else
+\echo [FAIL] (:testid) expected metadata rows in stale_doc2_cloudsync
+SELECT (:fail::int + 1) AS fail \gset
+\endif
+
+-- Cleanup
+\ir helper_test_cleanup.sql
+\if :should_cleanup
+DROP DATABASE IF EXISTS cloudsync_test_51;
+\else
+\echo [INFO] !!!!!
+\endif

test/postgresql/full_test.sql

@@ -58,6 +58,7 @@
 \ir 48_row_filter_multi_table.sql
 \ir 49_row_filter_prefill.sql
 \ir 50_block_lww_existing_data.sql
+\ir 51_stale_table_settings_dropped_meta.sql
 
 -- 'Test summary'
 \echo '\nTest summary:'