From 548209e620b3ca34396a360453f07c8dbb8aa6c7 Mon Sep 17 00:00:00 2001
From: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Date: Tue, 21 Oct 2025 21:11:44 +0200
Subject: [PATCH 1/2] Made RemoteTestResultTest.test_pickle_errors_detection()
 compatible with tblib 3.2+.

tblib 3.2+ makes exception subclasses with __init__() and the default
__reduce__() picklable. This broke the test for
RemoteTestResult._confirm_picklable(), which expects a specific
exception to fail unpickling.

https://github.com/ionelmc/python-tblib/blob/master/CHANGELOG.rst#320-2025-10-21

This fix defines ExceptionThatFailsUnpickling.__reduce__() in a way
that pickle.dumps(obj) succeeds, but pickle.loads(pickle.dumps(obj))
raises TypeError.

Refs #27301. This preserves the intent of the regression test from
52188a5ca6bafea0a66f17baacb315d61c7b99cd without skipping it.
---
 tests/test_runner/test_parallel.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tests/test_runner/test_parallel.py b/tests/test_runner/test_parallel.py
index fa129da76800..32cc971d305d 100644
--- a/tests/test_runner/test_parallel.py
+++ b/tests/test_runner/test_parallel.py
@@ -32,6 +32,12 @@ class ExceptionThatFailsUnpickling(Exception):
     def __init__(self, arg):
         super().__init__()
 
+    def __reduce__(self):
+        # tblib 3.2+ makes exception subclasses picklable by default.
+        # Return (cls, ()) so the constructor fails on unpickle, preserving
+        # the needed behavior for test_pickle_errors_detection.
+        return (self.__class__, ())
+
 
 class ParallelTestRunnerTest(SimpleTestCase):
     """
@@ -170,6 +176,8 @@ def test_pickle_errors_detection(self):
         result = RemoteTestResult()
         result._confirm_picklable(picklable_error)
 
+        # The exception can be pickled but not unpickled.
+        pickle.dumps(not_unpicklable_error)
         msg = "__init__() missing 1 required positional argument"
         with self.assertRaisesMessage(TypeError, msg):
             result._confirm_picklable(not_unpicklable_error)

From b6c9246d0a3ef5f9a40b15cc289b495351eae109 Mon Sep 17 00:00:00 2001
From: Jacob Walls <jacobtylerwalls@gmail.com>
Date: Tue, 21 Oct 2025 13:10:52 -0400
Subject: [PATCH 2/2] Fixed #36677 -- Fixed scheduling of system checks in
 ParallelTestSuite workers.

Running system checks in workers must happen after database aliases
are set up.

Regression in 606fc352799e372928fa2c978ab99f0fb6d6017c.
---
 django/test/runner.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/django/test/runner.py b/django/test/runner.py
index 25089a6db1b1..41c9dbd10ca9 100644
--- a/django/test/runner.py
+++ b/django/test/runner.py
@@ -463,9 +463,6 @@ def _init_worker(
             process_setup(*process_setup_args)
         django.setup()
         setup_test_environment(debug=debug_mode)
-        call_command(
-            "check", stdout=io.StringIO(), stderr=io.StringIO(), databases=used_aliases
-        )
 
     db_aliases = used_aliases if used_aliases is not None else connections
     for alias in db_aliases:
@@ -477,6 +474,11 @@ def _init_worker(
                 connection._test_serialized_contents = value
         connection.creation.setup_worker_connection(_worker_id)
 
+    if is_spawn_or_forkserver:
+        call_command(
+            "check", stdout=io.StringIO(), stderr=io.StringIO(), databases=used_aliases
+        )
+
 
 def _run_subsuite(args):
     """