bpo-35226: Fix equality for nested unittest.mock.call objects. (#10555)

Also refactor the call recording imolementation and add some notes
about its limitations.

Doc/library/unittest.mock-examples.rst

@@ -166,6 +166,15 @@ You use the :data:`call` object to construct lists for comparing with
     >>> mock.mock_calls == expected
     True
 
+However, parameters to calls that return mocks are not recorded, which means it is not
+possible to track nested calls where the parameters used to create ancestors are important:
+
+    >>> m = Mock()
+    >>> m.factory(important=True).deliver()
+    <Mock name='mock.factory().deliver()' id='...'>
+    >>> m.mock_calls[-1] == call.factory(important=False).deliver()
+    True
+
 
 Setting Return Values and Attributes
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Doc/library/unittest.mock.rst

@@ -702,6 +702,19 @@ the *new_callable* argument to :func:`patch`.
         unpacked as tuples to get at the individual arguments. See
         :ref:`calls as tuples <calls-as-tuples>`.
 
+        .. note::
+
+            The way :attr:`mock_calls` are recorded means that where nested
+            calls are made, the parameters of ancestor calls are not recorded
+            and so will always compare equal:
+
+                >>> mock = MagicMock()
+                >>> mock.top(a=3).bottom()
+                <MagicMock name='mock.top().bottom()' id='...'>
+                >>> mock.mock_calls
+                [call.top(a=3), call.top().bottom()]
+                >>> mock.mock_calls[-1] == call.top(a=-1).bottom()
+                True
 
     .. attribute:: __class__
 

Lib/unittest/mock.py

@@ -977,46 +977,51 @@ def _mock_call(_mock_self, *args, **kwargs):
         self = _mock_self
         self.called = True
         self.call_count += 1
-        _new_name = self._mock_new_name
-        _new_parent = self._mock_new_parent
 
+        # handle call_args
         _call = _Call((args, kwargs), two=True)
         self.call_args = _call
         self.call_args_list.append(_call)
-        self.mock_calls.append(_Call(('', args, kwargs)))
 
         seen = set()
-        skip_next_dot = _new_name == '()'
+
+        # initial stuff for method_calls:
         do_method_calls = self._mock_parent is not None
-        name = self._mock_name
+        method_call_name = self._mock_name
+
+        # initial stuff for mock_calls:
+        mock_call_name = self._mock_new_name
+        is_a_call = mock_call_name == '()'
+        self.mock_calls.append(_Call(('', args, kwargs)))
+
+        # follow up the chain of mocks:
+        _new_parent = self._mock_new_parent
         while _new_parent is not None:
-            this_mock_call = _Call((_new_name, args, kwargs))
-            if _new_parent._mock_new_name:
-                dot = '.'
-                if skip_next_dot:
-                    dot = ''
-
-                skip_next_dot = False
-                if _new_parent._mock_new_name == '()':
-                    skip_next_dot = True
-
-                _new_name = _new_parent._mock_new_name + dot + _new_name
 
+            # handle method_calls:
             if do_method_calls:
-                if _new_name == name:
-                    this_method_call = this_mock_call
-                else:
-                    this_method_call = _Call((name, args, kwargs))
-                _new_parent.method_calls.append(this_method_call)
-
+                _new_parent.method_calls.append(_Call((method_call_name, args, kwargs)))
                 do_method_calls = _new_parent._mock_parent is not None
                 if do_method_calls:
-                    name = _new_parent._mock_name + '.' + name
+                    method_call_name = _new_parent._mock_name + '.' + method_call_name
 
+            # handle mock_calls:
+            this_mock_call = _Call((mock_call_name, args, kwargs))
             _new_parent.mock_calls.append(this_mock_call)
+
+            if _new_parent._mock_new_name:
+                if is_a_call:
+                    dot = ''
+                else:
+                    dot = '.'
+                is_a_call = _new_parent._mock_new_name == '()'
+                mock_call_name = _new_parent._mock_new_name + dot + mock_call_name
+
+            # follow the parental chain:
             _new_parent = _new_parent._mock_new_parent
 
-            # use ids here so as not to call __hash__ on the mocks
+            # check we're not in an infinite loop:
+            # ( use ids here so as not to call __hash__ on the mocks)
             _new_parent_id = id(_new_parent)
             if _new_parent_id in seen:
                 break
@@ -2054,6 +2059,10 @@ def __eq__(self, other):
         else:
             self_name, self_args, self_kwargs = self
 
+        if (getattr(self, 'parent', None) and getattr(other, 'parent', None)
+                and self.parent != other.parent):
+            return False
+
         other_name = ''
         if len_other == 0:
             other_args, other_kwargs = (), {}

Lib/unittest/test/testmock/testhelpers.py

@@ -270,6 +270,22 @@ def test_extended_call(self):
         self.assertEqual(mock.mock_calls, last_call.call_list())
 
 
+    def test_extended_not_equal(self):
+        a = call(x=1).foo
+        b = call(x=2).foo
+        self.assertEqual(a, a)
+        self.assertEqual(b, b)
+        self.assertNotEqual(a, b)
+
+
+    def test_nested_calls_not_equal(self):
+        a = call(x=1).foo().bar
+        b = call(x=2).foo().bar
+        self.assertEqual(a, a)
+        self.assertEqual(b, b)
+        self.assertNotEqual(a, b)
+
+
     def test_call_list(self):
         mock = MagicMock()
         mock(1)

Lib/unittest/test/testmock/testmock.py

@@ -925,6 +925,57 @@ def test_mock_calls(self):
                              call().__int__().call_list())
 
 
+    def test_child_mock_call_equal(self):
+        m = Mock()
+        result = m()
+        result.wibble()
+        # parent looks like this:
+        self.assertEqual(m.mock_calls, [call(), call().wibble()])
+        # but child should look like this:
+        self.assertEqual(result.mock_calls, [call.wibble()])
+
+
+    def test_mock_call_not_equal_leaf(self):
+        m = Mock()
+        m.foo().something()
+        self.assertNotEqual(m.mock_calls[1], call.foo().different())
+        self.assertEqual(m.mock_calls[0], call.foo())
+
+
+    def test_mock_call_not_equal_non_leaf(self):
+        m = Mock()
+        m.foo().bar()
+        self.assertNotEqual(m.mock_calls[1], call.baz().bar())
+        self.assertNotEqual(m.mock_calls[0], call.baz())
+
+
+    def test_mock_call_not_equal_non_leaf_params_different(self):
+        m = Mock()
+        m.foo(x=1).bar()
+        # This isn't ideal, but there's no way to fix it without breaking backwards compatibility:
+        self.assertEqual(m.mock_calls[1], call.foo(x=2).bar())
+
+
+    def test_mock_call_not_equal_non_leaf_attr(self):
+        m = Mock()
+        m.foo.bar()
+        self.assertNotEqual(m.mock_calls[0], call.baz.bar())
+
+
+    def test_mock_call_not_equal_non_leaf_call_versus_attr(self):
+        m = Mock()
+        m.foo.bar()
+        self.assertNotEqual(m.mock_calls[0], call.foo().bar())
+
+
+    def test_mock_call_repr(self):
+        m = Mock()
+        m.foo().bar().baz.bob()
+        self.assertEqual(repr(m.mock_calls[0]), 'call.foo()')
+        self.assertEqual(repr(m.mock_calls[1]), 'call.foo().bar()')
+        self.assertEqual(repr(m.mock_calls[2]), 'call.foo().bar().baz.bob()')
+
+
     def test_subclassing(self):
         class Subclass(Mock):
             pass

Misc/NEWS.d/next/Library/2018-11-15-07-14-32.bpo-35226.wJPEEe.rst

@@ -0,0 +1,3 @@
+Recursively check arguments when testing for equality of
+:class:`unittest.mock.call` objects and add note that tracking of parameters
+used to create ancestors of mocks in ``mock_calls`` is not possible.