gh-100287: Fix unittest.mock.seal with AsyncMock (#100496)

Lib/test/test_unittest/testmock/testasync.py

@@ -11,7 +11,7 @@
 from asyncio import run, iscoroutinefunction
 from unittest import IsolatedAsyncioTestCase
 from unittest.mock import (ANY, call, AsyncMock, patch, MagicMock, Mock,
-                           create_autospec, sentinel, _CallList)
+                           create_autospec, sentinel, _CallList, seal)
 
 
 def tearDownModule():
@@ -300,6 +300,14 @@ def test_spec_normal_methods_on_class_with_mock(self):
         self.assertIsInstance(mock.async_method, AsyncMock)
         self.assertIsInstance(mock.normal_method, Mock)
 
+    def test_spec_normal_methods_on_class_with_mock_seal(self):
+        mock = Mock(AsyncClass)
+        seal(mock)
+        with self.assertRaises(AttributeError):
+            mock.normal_method
+        with self.assertRaises(AttributeError):
+            mock.async_method
+
     def test_spec_async_attributes_instance(self):
         async_instance = AsyncClass()
         async_instance.async_func_attr = async_func
@@ -1089,3 +1097,7 @@ async def f(x=None): pass
                         'Actual: [call(1)]'))) as cm:
             self.mock.assert_has_awaits([call(), call(1, 2)])
         self.assertIsInstance(cm.exception.__cause__, TypeError)
+
+
+if __name__ == '__main__':
+    unittest.main()

Lib/unittest/mock.py

@@ -1019,15 +1019,15 @@ def _get_child_mock(self, /, **kw):
 
         For non-callable mocks the callable variant will be used (rather than
         any custom subclass)."""
-        _new_name = kw.get("_new_name")
-        if _new_name in self.__dict__['_spec_asyncs']:
-            return AsyncMock(**kw)
-
         if self._mock_sealed:
             attribute = f".{kw['name']}" if "name" in kw else "()"
             mock_name = self._extract_mock_name() + attribute
             raise AttributeError(mock_name)
 
+        _new_name = kw.get("_new_name")
+        if _new_name in self.__dict__['_spec_asyncs']:
+            return AsyncMock(**kw)
+
         _type = type(self)
         if issubclass(_type, MagicMock) and _new_name in _async_method_magics:
             # Any asynchronous magic becomes an AsyncMock

Misc/NEWS.d/next/Library/2022-12-24-08-42-05.gh-issue-100287.n0oEuG.rst

@@ -0,0 +1 @@
+Fix the interaction of :func:`unittest.mock.seal` with :class:`unittest.mock.AsyncMock`.