bpo-45756: do not execute @property descrs while creating mock autospecs

Lib/unittest/mock.py

@@ -494,6 +494,10 @@ def _mock_add_spec(self, spec, spec_set, _spec_as_instance=False,
  _spec_asyncs = []
 
  for attr in dir(spec):
+ if isinstance(inspect.getattr_static(spec, attr, None), property):
+ # We don't want to execute `@property` decorators with `getattr`.
+ # It might affect user's code in unknown way.
+ continue
  if iscoroutinefunction(getattr(spec, attr, None)):
  _spec_asyncs.append(attr)
 

Lib/unittest/test/testmock/testmock.py

@@ -896,6 +896,36 @@ def set_attr():
  self.assertRaises(AttributeError, set_attr)
 
 
+ def test_class_with_property(self):
+ class X:
+ @property
+ def some(self):
+ raise ValueError('Should not be raised')
+
+ mock = Mock(spec=X)
+ self.assertIsInstance(mock, X)
+
+ mock = Mock(spec=X())
+ self.assertIsInstance(mock, X)
+
+
+ def test_class_with_settable_property(self):
+ class X:
+ @property
+ def some(self):
+ raise ValueError('Should not be raised')
+
+ @some.setter
+ def some(self, value):
+ raise TypeError('Should not be raised')
+
+ mock = Mock(spec=X)
+ self.assertIsInstance(mock, X)
+
+ mock = Mock(spec=X())
+ self.assertIsInstance(mock, X)
+
+
  def test_copy(self):
  current = sys.getrecursionlimit()
  self.addCleanup(sys.setrecursionlimit, current)

Misc/NEWS.d/next/Library/2021-12-03-11-19-44.bpo-45756.nSDJWj.rst

@@ -0,0 +1,2 @@
+We no longer execute ``@property`` descriptors while creating autospecs in
+``mock.py``. This was not safe and could affect user's code in unknown way.