From ce340bc0be2f19a12c06adba4eeb6a35ef6243d9 Mon Sep 17 00:00:00 2001
From: mikemikimike <13286568797@163.com>
Date: Sat, 29 Aug 2026 20:14:03 +0800
Subject: [PATCH 1/3] gh-156570: handle lazy warnings import in test helper

---
 Lib/test/support/warnings_helper.py |  2 +-
 Lib/test/test_warnings_helper.py    | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 Lib/test/test_warnings_helper.py

diff --git a/Lib/test/support/warnings_helper.py b/Lib/test/support/warnings_helper.py
index c046f39fbff511..93b3053a010089 100644
--- a/Lib/test/support/warnings_helper.py
+++ b/Lib/test/support/warnings_helper.py
@@ -173,7 +173,7 @@ def _filterwarnings(filters, quiet=False):
         registry.clear()
     # Because test_warnings swap the module, we need to look up in the
     # sys.modules dictionary.
-    wmod = sys.modules['warnings']
+    wmod = sys.modules.get('warnings', warnings)
     with wmod.catch_warnings(record=True) as w:
         # Set filter "always" to record all warnings.
         wmod.simplefilter("always")
diff --git a/Lib/test/test_warnings_helper.py b/Lib/test/test_warnings_helper.py
new file mode 100644
index 00000000000000..14f3cb79ef9721
--- /dev/null
+++ b/Lib/test/test_warnings_helper.py
@@ -0,0 +1,29 @@
+import sys
+import unittest
+from contextlib import contextmanager
+from unittest.mock import patch
+
+from test.support import warnings_helper
+
+
+class WarningsHelperTests(unittest.TestCase):
+    def test_check_warnings_when_module_is_not_in_sys_modules(self):
+        warnings_module = sys.modules.pop("warnings", None)
+        try:
+            @contextmanager
+            def catch_warnings(*, record):
+                self.assertTrue(record)
+                yield []
+
+            with patch.object(
+                warnings_helper.warnings, "catch_warnings", catch_warnings
+            ):
+                with warnings_helper.check_warnings(quiet=True):
+                    pass
+        finally:
+            if warnings_module is not None:
+                sys.modules["warnings"] = warnings_module
+
+
+if __name__ == "__main__":
+    unittest.main()

From 33f43fddfcae49a880011a2e319df2e056a0206e Mon Sep 17 00:00:00 2001
From: mikemikimike <13286568797@163.com>
Date: Sat, 29 Aug 2026 20:15:33 +0800
Subject: [PATCH 2/3] gh-156570: add news entry

---
 Misc/NEWS.d/next/Tests/20260829201500.gh-156570.rst | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Tests/20260829201500.gh-156570.rst

diff --git a/Misc/NEWS.d/next/Tests/20260829201500.gh-156570.rst b/Misc/NEWS.d/next/Tests/20260829201500.gh-156570.rst
new file mode 100644
index 00000000000000..3a7cd1492a3f85
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/20260829201500.gh-156570.rst
@@ -0,0 +1,2 @@
+Fix ``test.support.warnings_helper.check_warnings()`` failing with a
+``KeyError`` when lazy imports have not populated ``sys.modules``.

From d50c1faec77f023930aeec0d62a7bf20746aec55 Mon Sep 17 00:00:00 2001
From: mikemikimike <13286568797@163.com>
Date: Sat, 29 Aug 2026 20:16:38 +0800
Subject: [PATCH 3/3] gh-156570: fix news entry name

---
 ...h-156570.rst => 2026-08-29-20-15-00.gh-issue-156570.codex.rst} | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename Misc/NEWS.d/next/Tests/{20260829201500.gh-156570.rst => 2026-08-29-20-15-00.gh-issue-156570.codex.rst} (100%)

diff --git a/Misc/NEWS.d/next/Tests/20260829201500.gh-156570.rst b/Misc/NEWS.d/next/Tests/2026-08-29-20-15-00.gh-issue-156570.codex.rst
similarity index 100%
rename from Misc/NEWS.d/next/Tests/20260829201500.gh-156570.rst
rename to Misc/NEWS.d/next/Tests/2026-08-29-20-15-00.gh-issue-156570.codex.rst