From 186b50d49ef4f736e964b866702d90a5e4da1935 Mon Sep 17 00:00:00 2001
From: Matthias Schoettle <git@mattsch.com>
Date: Thu, 19 Mar 2026 22:39:41 -0400
Subject: [PATCH] gh-145754: Update signature retrieval in unittest.mock to use
 forwardref annotation format (GH-145756) (cherry picked from commit
 d357a7dbf38868844415ec1d5df80379ea5a2326)

Co-authored-by: Matthias Schoettle <git@mattsch.com>
---
 Lib/test/test_unittest/testmock/testmock.py                | 7 +++++++
 Lib/unittest/mock.py                                       | 3 ++-
 .../Library/2026-03-10-14-57-15.gh-issue-145754.YBL5Ko.rst | 2 ++
 3 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2026-03-10-14-57-15.gh-issue-145754.YBL5Ko.rst

diff --git a/Lib/test/test_unittest/testmock/testmock.py b/Lib/test/test_unittest/testmock/testmock.py
index 386d53bf5a5c63..764585ec5d5468 100644
--- a/Lib/test/test_unittest/testmock/testmock.py
+++ b/Lib/test/test_unittest/testmock/testmock.py
@@ -1743,6 +1743,13 @@ def static_method(): pass
                 mock_method.assert_called_once_with()
                 self.assertRaises(TypeError, mock_method, 'extra_arg')
 
+    # gh-145754
+    def test_create_autospec_type_hints_typechecking(self):
+        def foo(x: Tuple[int, ...]) -> None:
+            pass
+
+        mock.create_autospec(foo)
+
     #Issue21238
     def test_mock_unsafe(self):
         m = Mock()
diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 545b0730d2e039..92b81d1584142e 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -34,6 +34,7 @@
 import pkgutil
 from inspect import iscoroutinefunction
 import threading
+from annotationlib import Format
 from dataclasses import fields, is_dataclass
 from types import CodeType, ModuleType, MethodType
 from unittest.util import safe_repr
@@ -119,7 +120,7 @@ def _get_signature_object(func, as_instance, eat_self):
     else:
         sig_func = func
     try:
-        return func, inspect.signature(sig_func)
+        return func, inspect.signature(sig_func, annotation_format=Format.FORWARDREF)
     except ValueError:
         # Certain callable types are not supported by inspect.signature()
         return None
diff --git a/Misc/NEWS.d/next/Library/2026-03-10-14-57-15.gh-issue-145754.YBL5Ko.rst b/Misc/NEWS.d/next/Library/2026-03-10-14-57-15.gh-issue-145754.YBL5Ko.rst
new file mode 100644
index 00000000000000..7de81ac19c2efa
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-03-10-14-57-15.gh-issue-145754.YBL5Ko.rst
@@ -0,0 +1,2 @@
+Request signature during mock autospec with ``FORWARDREF`` annotation format.
+This prevents runtime errors when an annotation uses a name that is not defined at runtime.