[3.13] gh-65454: avoid triggering call to a PropertyMock in NonCallableMock.__setattr__ (GH-120019)

Lib/test/test_unittest/testmock/testhelpers.py

@@ -1127,6 +1127,14 @@ def test_propertymock_side_effect(self):
         p.assert_called_once_with()
 
 
+    def test_propertymock_attach(self):
+        m = Mock()
+        p = PropertyMock()
+        type(m).foo = p
+        m.attach_mock(p, 'foo')
+        self.assertEqual(m.mock_calls, [])
+
+
 class TestCallablePredicate(unittest.TestCase):
 
     def test_type(self):

Lib/unittest/mock.py

@@ -830,6 +830,9 @@ def __setattr__(self, name, value):
             mock_name = f'{self._extract_mock_name()}.{name}'
             raise AttributeError(f'Cannot set {mock_name}')
 
+        if isinstance(value, PropertyMock):
+            self.__dict__[name] = value
+            return
         return object.__setattr__(self, name, value)
 
 

Misc/NEWS.d/next/Library/2024-06-04-08-57-02.gh-issue-65454.o9j4wF.rst

@@ -0,0 +1 @@
+:func:`unittest.mock.Mock.attach_mock` no longer triggers a call to a ``PropertyMock`` being attached.