Skip isolation tests that terminate other backends on Windows

On Windows, a backend exiting resets its connection, and the client
discards any data not yet read, including the FATAL message of a
terminated backend.  isolationtester polls one connection at a time, so
when it waits on a different session the message can get lost, failing
the permutation and the tests that run after it.

wait_cleanup in injection_points (down to v17) and slot_creation_error
in test_decoding (down to v15) have this pattern, and have been failing
randomly in the buildfarm.  Let's skip them on Windows.

The cause of the instabilities is proving to be tricky to deal with,
pointing for example at 29992a6a50.  This will be tackled later,
perhaps with a backpatch (or perhaps with a HEAD-only solution), but it
is difficult to be sure at this stage of the work.  In theory,
a8458f508a should make a revert of 29992a6a50 (revert of a revert!)
safe on WIN32.

Note that 278cdea6b9, that has introduced the isolation test
slot_creation_error in test_decoding, has mentioned the potential output
instability.

Author: Zsolt Parragi <zsolt.parragi@percona.com>
Author: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAN4CZFOoiKa9E4Gnh_OzLk3S5Z6RFyg_oY1e_WddCVYhkpTVow@mail.gmail.com
Backpatch-through: 15

contrib/test_decoding/Makefile

@@ -6,9 +6,15 @@ PGFILEDESC = "test_decoding - example of a logical decoding output plugin"
 REGRESS = ddl xact rewrite toast permissions decoding_in_xact \
 	decoding_into_rel binary prepared replorigin time messages \
 	repack spill slot truncate stream stats twophase twophase_stream
+
+# slot_creation_error terminates another backend, whose FATAL message can be
+# lost on Windows, making the test unstable there.
+# See https://postgr.es/m/088AB35D-0860-494A-A9CF-8B301543AA51@yandex-team.ru
+SLOT_CREATION_TST = $(if $(filter win32,$(PORTNAME)),,slot_creation_error)
+
 ISOLATION = mxact delayed_startup ondisk_startup concurrent_ddl_dml \
 	oldest_xmin snapshot_transfer subxact_without_top concurrent_stream \
-	twophase_snapshot slot_creation_error catalog_change_snapshot \
+	twophase_snapshot $(SLOT_CREATION_TST) catalog_change_snapshot \
 	skip_snapshot_restore invalidation_distribution parallel_session_origin
 
 REGRESS_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf

contrib/test_decoding/meson.build

@@ -16,6 +16,29 @@ test_decoding = shared_module('test_decoding',
 )
 contrib_targets += test_decoding
 
+test_decoding_isolation = [
+  'mxact',
+  'delayed_startup',
+  'ondisk_startup',
+  'catalog_change_snapshot',
+  'concurrent_ddl_dml',
+  'oldest_xmin',
+  'snapshot_transfer',
+  'subxact_without_top',
+  'concurrent_stream',
+  'twophase_snapshot',
+  'skip_snapshot_restore',
+  'invalidation_distribution',
+  'parallel_session_origin',
+]
+
+# slot_creation_error terminates another backend, whose FATAL message can be
+# lost on Windows, making the test unstable there.
+# See https://postgr.es/m/088AB35D-0860-494A-A9CF-8B301543AA51@yandex-team.ru
+if host_system != 'windows'
+  test_decoding_isolation += 'slot_creation_error'
+endif
+
 tests += {
   'name': 'test_decoding',
   'sd': meson.current_source_dir(),
@@ -51,22 +74,7 @@ tests += {
     'runningcheck': false,
   },
   'isolation': {
-    'specs': [
-      'mxact',
-      'delayed_startup',
-      'ondisk_startup',
-      'catalog_change_snapshot',
-      'concurrent_ddl_dml',
-      'oldest_xmin',
-      'snapshot_transfer',
-      'subxact_without_top',
-      'concurrent_stream',
-      'twophase_snapshot',
-      'slot_creation_error',
-      'skip_snapshot_restore',
-      'invalidation_distribution',
-      'parallel_session_origin',
-    ],
+    'specs': test_decoding_isolation,
     'regress_args': [
       '--temp-config', files('logical.conf'),
     ],

src/test/modules/injection_points/Makefile

@@ -14,6 +14,11 @@ EXTRA_INSTALL = contrib/test_decoding
 REGRESS = injection_points hashagg reindex_conc vacuum
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
+# wait_cleanup terminates another backend, whose FATAL message can be lost
+# on Windows, making the test unstable there.
+# See https://postgr.es/m/088AB35D-0860-494A-A9CF-8B301543AA51@yandex-team.ru
+WAIT_CLEANUP_TST = $(if $(filter win32,$(PORTNAME)),,wait_cleanup)
+
 ISOLATION = basic \
 	    inplace \
 	    reindex_concurrently_deferred \
@@ -27,7 +32,7 @@ ISOLATION = basic \
 	    ri_fastpath_reindex \
 	    ri_fastpath_snapshot \
 	    syscache-update-pruned \
-	    wait_cleanup \
+	    $(WAIT_CLEANUP_TST) \
 	    heap_lock_update \
 	    on_conflict_probe_window
 

src/test/modules/injection_points/meson.build

@@ -26,6 +26,32 @@ test_install_data += files(
   'injection_points--1.0.sql',
 )
 
+injection_points_isolation = [
+  'basic',
+  'inplace',
+  'reindex_concurrently_deferred',
+  'repack',
+  'repack_commit_race',
+  'repack_decode',
+  'repack_dropped',
+  'repack_missingval',
+  'repack_temporal',
+  'repack_temporal_multirange',
+  'repack_toast',
+  'ri_fastpath_reindex',
+  'ri_fastpath_snapshot',
+  'syscache-update-pruned',
+  'heap_lock_update',
+  'on_conflict_probe_window',
+]
+
+# wait_cleanup terminates another backend, whose FATAL message can be lost
+# on Windows, making the test unstable there.
+# See https://postgr.es/m/088AB35D-0860-494A-A9CF-8B301543AA51@yandex-team.ru
+if host_system != 'windows'
+  injection_points_isolation += 'wait_cleanup'
+endif
+
 tests += {
   'name': 'injection_points',
   'sd': meson.current_source_dir(),
@@ -42,25 +68,7 @@ tests += {
     'runningcheck': false,
   },
   'isolation': {
-    'specs': [
-      'basic',
-      'inplace',
-      'reindex_concurrently_deferred',
-      'repack',
-      'repack_commit_race',
-      'repack_decode',
-      'repack_dropped',
-      'repack_missingval',
-      'repack_temporal',
-      'repack_temporal_multirange',
-      'repack_toast',
-      'ri_fastpath_reindex',
-      'ri_fastpath_snapshot',
-      'syscache-update-pruned',
-      'wait_cleanup',
-      'heap_lock_update',
-      'on_conflict_probe_window',
-    ],
+    'specs': injection_points_isolation,
     'runningcheck': false, # see syscache-update-pruned
     # Some tests wait for all snapshots, so avoid parallel execution
     'runningcheck-parallel': false,