bpo-38108: Makes mock objects inherit from Base (GH-16060)

Backports: 9a7d9519506ae807ca48ff02e2ea117ebac3450e
Signed-off-by: Chris Withers <chris@withers.org>

NEWS.d/2019-09-25-21-37-02.bpo-38108.Jr9HU6.rst

@@ -0,0 +1,2 @@
+Any synchronous magic methods on an AsyncMock now return a MagicMock. Any
+asynchronous magic methods on a MagicMock now return an AsyncMock.

mock/mock.py

@@ -411,7 +411,7 @@ def __new__(cls, *args, **kw):
             if spec_arg and _is_async_obj(spec_arg):
                 bases = (AsyncMockMixin, cls)
         new = type(cls.__name__, bases, {'__doc__': cls.__doc__})
-        instance = object.__new__(new)
+        instance = _safe_super(NonCallableMock, cls).__new__(new)
         return instance
 
 
@@ -997,17 +997,18 @@ def _get_child_mock(self, **kw):
 
         _type = type(self)
         if issubclass(_type, MagicMock) and _new_name in _async_method_magics:
+            # Any asynchronous magic becomes an AsyncMock
             klass = AsyncMock
-        elif _new_name  in _sync_async_magics:
-            # Special case these ones b/c users will assume they are async,
-            # but they are actually sync (ie. __aiter__)
-            klass = MagicMock
         elif issubclass(_type, AsyncMockMixin):
-            klass = AsyncMock
+            if _new_name in _all_sync_magics:
+                # Any synchronous magic becomes a MagicMock
+                klass = MagicMock
+            else:
+                klass = AsyncMock
         elif not issubclass(_type, CallableMixin):
             if issubclass(_type, NonCallableMagicMock):
                 klass = MagicMock
-            elif issubclass(_type, NonCallableMock) :
+            elif issubclass(_type, NonCallableMock):
                 klass = Mock
         else:
             klass = _type.__mro__[1]
@@ -1895,6 +1896,7 @@ def _patch_stopall():
     "round trunc floor ceil "
     "bool next "
     "fspath "
+    "aiter "
 )
 
 if IS_PYPY:
@@ -2037,21 +2039,22 @@ def _set_return_value(mock, method, name):
 
 
 
-class MagicMixin(object):
+class MagicMixin(Base):
     def __init__(self, *args, **kw):
         self._mock_set_magics()  # make magic work for kwargs in init
         _safe_super(MagicMixin, self).__init__(*args, **kw)
         self._mock_set_magics()  # fix magic broken by upper level init
 
 
     def _mock_set_magics(self):
-        these_magics = _magics
+        orig_magics = _magics | _async_method_magics
+        these_magics = orig_magics
 
         if getattr(self, "_mock_methods", None) is not None:
-            these_magics = _magics.intersection(self._mock_methods)
+            these_magics = orig_magics.intersection(self._mock_methods)
 
             remove_magics = set()
-            remove_magics = _magics - these_magics
+            remove_magics = orig_magics - these_magics
 
             for entry in remove_magics:
                 if entry in type(self).__dict__:
@@ -2079,33 +2082,14 @@ def mock_add_spec(self, spec, spec_set=False):
         self._mock_set_magics()
 
 
-class AsyncMagicMixin:
+class AsyncMagicMixin(MagicMixin):
     def __init__(self, *args, **kw):
-        self._mock_set_async_magics()  # make magic work for kwargs in init
+        self._mock_set_magics()  # make magic work for kwargs in init
         _safe_super(AsyncMagicMixin, self).__init__(*args, **kw)
-        self._mock_set_async_magics()  # fix magic broken by upper level init
-
-    def _mock_set_async_magics(self):
-        these_magics = _async_magics
-
-        if getattr(self, "_mock_methods", None) is not None:
-            these_magics = _async_magics.intersection(self._mock_methods)
-            remove_magics = _async_magics - these_magics
-
-            for entry in remove_magics:
-                if entry in type(self).__dict__:
-                    # remove unneeded magic methods
-                    delattr(self, entry)
-
-        # don't overwrite existing attributes if called a second time
-        these_magics = these_magics - set(type(self).__dict__)
-
-        _type = type(self)
-        for entry in these_magics:
-            setattr(_type, entry, MagicProxy(entry, self))
+        self._mock_set_magics()  # fix magic broken by upper level init
 
 
-class MagicMock(MagicMixin, AsyncMagicMixin, Mock):
+class MagicMock(MagicMixin, Mock):
     """
     MagicMock is a subclass of Mock with default implementations
     of most of the magic methods. You can use MagicMock without having to
@@ -2127,7 +2111,7 @@ def mock_add_spec(self, spec, spec_set=False):
 
 
 
-class MagicProxy(object):
+class MagicProxy(Base):
     def __init__(self, name, parent):
         self.name = name
         self.parent = parent

mock/tests/testasync.py

@@ -393,6 +393,43 @@ def test_add_side_effect_iterable(self):
                 RuntimeError('coroutine raised StopIteration')
             )
 
+class AsyncMagicMethods(unittest.TestCase):
+    def test_async_magic_methods_return_async_mocks(self):
+        m_mock = MagicMock()
+        self.assertIsInstance(m_mock.__aenter__, AsyncMock)
+        self.assertIsInstance(m_mock.__aexit__, AsyncMock)
+        self.assertIsInstance(m_mock.__anext__, AsyncMock)
+        # __aiter__ is actually a synchronous object
+        # so should return a MagicMock
+        self.assertIsInstance(m_mock.__aiter__, MagicMock)
+
+    def test_sync_magic_methods_return_magic_mocks(self):
+        a_mock = AsyncMock()
+        self.assertIsInstance(a_mock.__enter__, MagicMock)
+        self.assertIsInstance(a_mock.__exit__, MagicMock)
+        self.assertIsInstance(a_mock.__next__, MagicMock)
+        self.assertIsInstance(a_mock.__len__, MagicMock)
+
+    def test_magicmock_has_async_magic_methods(self):
+        m_mock = MagicMock()
+        self.assertTrue(hasattr(m_mock, "__aenter__"))
+        self.assertTrue(hasattr(m_mock, "__aexit__"))
+        self.assertTrue(hasattr(m_mock, "__anext__"))
+
+    def test_asyncmock_has_sync_magic_methods(self):
+        a_mock = AsyncMock()
+        self.assertTrue(hasattr(a_mock, "__enter__"))
+        self.assertTrue(hasattr(a_mock, "__exit__"))
+        self.assertTrue(hasattr(a_mock, "__next__"))
+        self.assertTrue(hasattr(a_mock, "__len__"))
+
+    def test_magic_methods_are_async_functions(self):
+        m_mock = MagicMock()
+        self.assertIsInstance(m_mock.__aenter__, AsyncMock)
+        self.assertIsInstance(m_mock.__aexit__, AsyncMock)
+        # AsyncMocks are also coroutine functions
+        self.assertTrue(asyncio.iscoroutinefunction(m_mock.__aenter__))
+        self.assertTrue(asyncio.iscoroutinefunction(m_mock.__aexit__))
 
 class AsyncContextManagerTest(unittest.TestCase):
 
@@ -420,24 +457,6 @@ async def main(self):
                 val = await response.json()
                 return val
 
-    def test_async_magic_methods_are_async_mocks_with_magicmock(self):
-        cm_mock = MagicMock(self.WithAsyncContextManager())
-        self.assertIsInstance(cm_mock.__aenter__, AsyncMock)
-        self.assertIsInstance(cm_mock.__aexit__, AsyncMock)
-
-    def test_magicmock_has_async_magic_methods(self):
-        cm = MagicMock(name='magic_cm')
-        self.assertTrue(hasattr(cm, "__aenter__"))
-        self.assertTrue(hasattr(cm, "__aexit__"))
-
-    def test_magic_methods_are_async_functions(self):
-        cm = MagicMock(name='magic_cm')
-        self.assertIsInstance(cm.__aenter__, AsyncMock)
-        self.assertIsInstance(cm.__aexit__, AsyncMock)
-        # AsyncMocks are also coroutine functions
-        self.assertTrue(asyncio.iscoroutinefunction(cm.__aenter__))
-        self.assertTrue(asyncio.iscoroutinefunction(cm.__aexit__))
-
     def test_set_return_value_of_aenter(self):
         def inner_test(mock_type):
             pc = self.ProductionCode()
@@ -909,7 +928,7 @@ def test_assert_has_awaits_not_matching_spec_error(self):
         async def f(x=None): pass
 
         self.mock = AsyncMock(spec=f)
-        asyncio.run(self._runnable_test(1))
+        run(self._runnable_test(1))
 
         with self.assertRaisesRegex(
                 AssertionError,

mock/tests/testmagicmethods.py

@@ -271,9 +271,6 @@ def test_magic_mock_equality(self):
         self.assertEqual(mock == mock, True)
         self.assertEqual(mock != mock, False)
 
-
-    # This should be fixed with issue38163
-    @unittest.expectedFailure
     def test_asyncmock_defaults(self):
         mock = AsyncMock()
         self.assertEqual(int(mock), 1)