Rearrange core regression tests to reduce cross-script dependencies.

The idea behind this patch is to make it possible to run individual
test scripts without running the entire core test suite.  Making all
the scripts completely independent would involve a massive rewrite,
and would probably be worse for coverage of things like concurrent DDL.
So this patch just does what seems practical with limited changes.

The net effect is that any test script can be run after running
limited earlier dependencies:
* all scripts depend on test_setup
* many scripts depend on create_index
* other dependencies are few in number, and are documented in
  the parallel_schedule file.

To accomplish this, I chose a small number of commonly-used tables
and moved their creation and filling into test_setup.  Later scripts
are expected not to modify these tables' data contents, for fear of
affecting other scripts' results.  Also, our former habit of declaring
all C functions in one place is now gone in favor of declaring them
where they're used, if that's just one script, or in test_setup if
necessary.

There's more that could be done to remove some of the remaining
inter-script dependencies, but significantly more-invasive changes
would be needed, and at least for now it doesn't seem worth it.

Discussion: https://postgr.es/m/1114748.1640383217@sss.pgh.pa.us

1 files changed, 8 insertions, 0 deletions

diff --git a/src/test/regress/expected/foreign_data.out b/src/test/regress/expected/foreign_data.out
index a6a68d1fa2..5bf03680d2 100644
--- a/src/test/regress/expected/foreign_data.out
+++ b/src/test/regress/expected/foreign_data.out
@@ -1,6 +1,14 @@
 --
 -- Test foreign-data wrapper and server management.
 --
+-- directory paths and dlsuffix are passed to us in environment variables
+\getenv libdir PG_LIBDIR
+\getenv dlsuffix PG_DLSUFFIX
+\set regresslib :libdir '/regress' :dlsuffix
+CREATE FUNCTION test_fdw_handler()
+    RETURNS fdw_handler
+    AS :'regresslib', 'test_fdw_handler'
+    LANGUAGE C;
 -- Clean up in case a prior regression run failed
 -- Suppress NOTICE messages when roles don't exist
 SET client_min_messages TO 'warning';