gh-103329: Add regression test for PropertyMock with side effect (#103358)

Backports: 26c65980dc6d842879d133165bb7c461d98cc6c7
Signed-off-by: Chris Withers <chris@simplistix.co.uk>

Author: freakboy3742

NEWS.d/2023-04-08-00-50-23.gh-issue-103329.M38tqF.rst

@@ -0,0 +1 @@
+Regression tests for the behaviour of ``unittest.mock.PropertyMock`` were added.

mock/tests/testhelpers.py

@@ -1086,7 +1086,7 @@ def test_propertymock(self):
             p.stop()
 
 
-    def test_propertymock_returnvalue(self):
+    def test_propertymock_bare(self):
         m = MagicMock()
         p = PropertyMock()
         type(m).foo = p
@@ -1097,6 +1097,27 @@ def test_propertymock_returnvalue(self):
         self.assertNotIsInstance(returned, PropertyMock)
 
 
+    def test_propertymock_returnvalue(self):
+        m = MagicMock()
+        p = PropertyMock(return_value=42)
+        type(m).foo = p
+
+        returned = m.foo
+        p.assert_called_once_with()
+        self.assertEqual(returned, 42)
+        self.assertNotIsInstance(returned, PropertyMock)
+
+
+    def test_propertymock_side_effect(self):
+        m = MagicMock()
+        p = PropertyMock(side_effect=ValueError)
+        type(m).foo = p
+
+        with self.assertRaises(ValueError):
+            m.foo
+        p.assert_called_once_with()
+
+
 class TestCallablePredicate(unittest.TestCase):
 
     def test_type(self):