gh-156460: Test synchronous callable side effects

Author: cananoo

Lib/test/test_unittest/testmock/testasync.py

@@ -477,6 +477,15 @@ async def __call__(self, var):
         result = await mock(5)
         self.assertEqual(result, 6)
 
+    async def test_add_side_effect_sync_callable(self):
+        class SyncCallable:
+            def __call__(self, var):
+                return var + 1
+
+        mock = AsyncMock(side_effect=SyncCallable())
+        result = await mock(5)
+        self.assertEqual(result, 6)
+
     async def test_add_side_effect_normal_function(self):
         def addition(var):
             return var + 1

Misc/NEWS.d/next/Library/2026-08-27-20-47-01.gh-issue-156460.A7kP3m.rst

@@ -1,2 +1,2 @@
-Await async callable objects used as the ``side_effect`` of
+Correctly handle async callable objects used as the ``side_effect`` of
 :class:`unittest.mock.AsyncMock`.