bpo-38932: Make Mock.reset_mock() pass return_value and side_effect values to reset_mock on child mock objects

Lib/unittest/mock.py

@@ -592,7 +592,7 @@ def reset_mock(self,  visited=None,*, return_value=False, side_effect=False):
         for child in self._mock_children.values():
             if isinstance(child, _SpecState) or child is _deleted:
                 continue
-            child.reset_mock(visited)
+            child.reset_mock(visited, return_value=return_value, side_effect=side_effect)
 
         ret = self._mock_return_value
         if _is_instance_mock(ret) and ret is not self:

Lib/unittest/test/testmock/testmock.py

@@ -1636,11 +1636,23 @@ def test_reset_return(self):
         self.assertNotEqual(m.side_effect, None)
 
     def test_reset_sideeffect(self):
-        m = Mock(return_value=10, side_effect=[2,3])
+        m = Mock(return_value=10, side_effect=[2, 3])
         m.reset_mock(side_effect=True)
         self.assertEqual(m.return_value, 10)
         self.assertEqual(m.side_effect, None)
 
+    def test_reset_return_with_children(self):
+        m = MagicMock(f=MagicMock(return_value=1))
+        self.assertEqual(m.f(), 1)
+        m.reset_mock(return_value=True)
+        self.assertNotEqual(m.f(), 1)
+
+    def test_reset_return_with_children_side_effect(self):
+        m = MagicMock(f=MagicMock(side_effect=[2, 3]))
+        self.assertNotEqual(m.f.side_effect, None)
+        m.reset_mock(side_effect=True)
+        self.assertEqual(m.f.side_effect, None)
+
     def test_mock_add_spec(self):
         class _One(object):
             one = 1

Misc/NEWS.d/next/Library/2020-01-25-13-41-27.bpo-38932.1pu_8I.rst

@@ -0,0 +1 @@
+Mock fully resets child objects on reset_mock(). Patch by Vegard Stikbakke