bpo-21478: Record calls to parent when autospecced objects are used as child with attach_mock (GH 14688)

* Clear name and parent of mock in autospecced objects used with attach_mock

* Add NEWS entry

* Fix reversed order of comparison

* Test child and standalone function calls

* Use a helper function extracting mock to avoid code duplication and refactor tests.

Author: tirkarthi

Lib/unittest/mock.py

@@ -72,6 +72,15 @@ def _is_exception(obj):
     )
 
 
+def _extract_mock(obj):
+    # Autospecced functions will return a FunctionType with "mock" attribute
+    # which is the actual mock object that needs to be used.
+    if isinstance(obj, FunctionTypes) and hasattr(obj, 'mock'):
+        return obj.mock
+    else:
+        return obj
+
+
 def _get_signature_object(func, as_instance, eat_self):
     """
     Given an arbitrary, possibly callable object, try to create a suitable
@@ -346,13 +355,7 @@ def __repr__(self):
 
 
 def _check_and_set_parent(parent, value, name, new_name):
-    # function passed to create_autospec will have mock
-    # attribute attached to which parent must be set
-    if isinstance(value, FunctionTypes):
-        try:
-            value = value.mock
-        except AttributeError:
-            pass
+    value = _extract_mock(value)
 
     if not _is_instance_mock(value):
         return False
@@ -467,10 +470,12 @@ def attach_mock(self, mock, attribute):
         Attach a mock as an attribute of this one, replacing its name and
         parent. Calls to the attached mock will be recorded in the
         `method_calls` and `mock_calls` attributes of this one."""
-        mock._mock_parent = None
-        mock._mock_new_parent = None
-        mock._mock_name = ''
-        mock._mock_new_name = None
+        inner_mock = _extract_mock(mock)
+
+        inner_mock._mock_parent = None
+        inner_mock._mock_new_parent = None
+        inner_mock._mock_name = ''
+        inner_mock._mock_new_name = None
 
         setattr(self, attribute, mock)
 

Lib/unittest/test/testmock/testmock.py

@@ -37,6 +37,9 @@ def cmeth(cls, a, b, c, d=None): pass
     def smeth(a, b, c, d=None): pass
 
 
+def something(a): pass
+
+
 class MockTest(unittest.TestCase):
 
     def test_all(self):
@@ -1808,6 +1811,26 @@ def test_attach_mock_return_value(self):
                 self.assertEqual(m.mock_calls, call().foo().call_list())
 
 
+    def test_attach_mock_patch_autospec(self):
+        parent = Mock()
+
+        with mock.patch(f'{__name__}.something', autospec=True) as mock_func:
+            self.assertEqual(mock_func.mock._extract_mock_name(), 'something')
+            parent.attach_mock(mock_func, 'child')
+            parent.child(1)
+            something(2)
+            mock_func(3)
+
+            parent_calls = [call.child(1), call.child(2), call.child(3)]
+            child_calls = [call(1), call(2), call(3)]
+            self.assertEqual(parent.mock_calls, parent_calls)
+            self.assertEqual(parent.child.mock_calls, child_calls)
+            self.assertEqual(something.mock_calls, child_calls)
+            self.assertEqual(mock_func.mock_calls, child_calls)
+            self.assertIn('mock.child', repr(parent.child.mock))
+            self.assertEqual(mock_func.mock._extract_mock_name(), 'mock.child')
+
+
     def test_attribute_deletion(self):
         for mock in (Mock(), MagicMock(), NonCallableMagicMock(),
                      NonCallableMock()):
@@ -1891,6 +1914,20 @@ def foo(a, b): pass
 
         self.assertRaises(TypeError, mock.child, 1)
         self.assertEqual(mock.mock_calls, [call.child(1, 2)])
+        self.assertIn('mock.child', repr(mock.child.mock))
+
+    def test_parent_propagation_with_autospec_attach_mock(self):
+
+        def foo(a, b): pass
+
+        parent = Mock()
+        parent.attach_mock(create_autospec(foo, name='bar'), 'child')
+        parent.child(1, 2)
+
+        self.assertRaises(TypeError, parent.child, 1)
+        self.assertEqual(parent.child.mock_calls, [call.child(1, 2)])
+        self.assertIn('mock.child', repr(parent.child.mock))
+
 
     def test_isinstance_under_settrace(self):
         # bpo-36593 : __class__ is not set for a class that has __class__

Misc/NEWS.d/next/Library/2019-07-10-23-07-11.bpo-21478.cCw9rF.rst

@@ -0,0 +1,2 @@
+Record calls to parent when autospecced object is attached to a mock using
+:func:`unittest.mock.attach_mock`. Patch by Karthikeyan Singaravelan.