src/test/regress/expected/hooktest.source

LOAD '@abs_builddir@/hooktest/test_hook@DLSUFFIX@';
-----------------------------------
-- Test planner hook
-----------------------------------
SET client_min_messages='log';
SELECT 1 AS a;
LOG:  statement: SELECT 1 AS a;
LOG:  In test_planner_hook
 a 
---
 1
(1 row)