test: cover stale schema cache database error

Add an IO test that drops a table while schema cache reload is delayed. It verifies the stale cache path returns PostgreSQL 42P01 and the refreshed cache returns PGRST205.

Author: mkleczek

test/io/test_io.py

@@ -31,6 +31,20 @@
 )
 
 
+def psql_as_superuser(query):
+    subprocess.check_call(
+        [
+            "psql",
+            "--username",
+            "postgres",
+            "--set",
+            "ON_ERROR_STOP=1",
+            "-c",
+            query,
+        ]
+    )
+
+
 def test_connect_with_dburi(dburi, defaultenv):
     "Connecting with db-uri instead of LIPQ* environment variables should work."
     defaultenv_without_libpq = {
@@ -1204,6 +1218,61 @@ def test_notify_reloading_catalog_cache(defaultenv):
         assert response.status_code == 200
 
 
+def test_stale_schema_cache_dropped_table_returns_database_error(defaultenv):
+    "dropped table should return a database error while schema cache is stale"
+
+    table = "stale_schema_cache_items"
+    internal_sleep = 2
+    env = {
+        **defaultenv,
+        "PGRST_DB_POOL": "2",
+        "PGRST_DB_CHANNEL_ENABLED": "true",
+        "PGRST_INTERNAL_SCHEMA_CACHE_QUERY_SLEEP": str(internal_sleep * 1000),
+    }
+    path = f"/{table}"
+
+    try:
+        psql_as_superuser(
+            f"""
+            drop table if exists {table};
+            create table {table}(id int primary key);
+            insert into {table} values (1);
+            grant select on {table} to postgrest_test_anonymous;
+            """
+        )
+
+        with run(env=env, wait_max_seconds=10) as postgrest:
+            response = postgrest.session.get(path)
+            assert response.status_code == 200
+            assert response.json() == [{"id": 1}]
+
+            psql_as_superuser(
+                f"""
+                drop table {table};
+                notify pgrst, 'reload schema';
+                """
+            )
+
+            response = postgrest.session.get(path)
+            payload = response.json()
+            assert response.status_code == 404
+            assert payload["code"] == "42P01"
+            assert payload["message"] == f'relation "public.{table}" does not exist'
+
+            time.sleep(internal_sleep + 0.3)
+
+            response = postgrest.session.get(path)
+            assert response.status_code == 404
+            assert response.json() == {
+                "code": "PGRST205",
+                "details": None,
+                "hint": None,
+                "message": f"Could not find the table 'public.{table}' in the schema cache",
+            }
+    finally:
+        psql_as_superuser(f"drop table if exists {table};")
+
+
 def test_role_settings(defaultenv):
     "statement_timeout should be set per role"