bpo-37251: Removes __code__ check from _is_async_obj. (GH-15830)

Backports: f1a297acb60b88917712450ebd3cfa707e6efd6b
Signed-off-by: Chris Withers <chris@withers.org>

NEWS.d/2019-09-10-10-59-50.bpo-37251.8zn2o3.rst

diff --git a/NEWS.d/2019-09-10-10-59-50.bpo-37251.8zn2o3.rst b/NEWS.d/2019-09-10-10-59-50.bpo-37251.8zn2o3.rst
new file mode 100644
index 0000000..27fd1e4
--- /dev/null
+++ b/NEWS.d/2019-09-10-10-59-50.bpo-37251.8zn2o3.rst
@@ -0,0 +1,3 @@
+Remove `__code__` check in AsyncMock that incorrectly
+evaluated function specs as async objects but failed to evaluate classes
+with `__await__` but no `__code__` attribute defined as async objects.

mock/mock.py

diff --git a/mock/mock.py b/mock/mock.py
index 2d4d89e..8a9fc9d 100644
--- a/mock/mock.py
+++ b/mock/mock.py
@@ -47,10 +47,9 @@
 _safe_super = super
 
 def _is_async_obj(obj):
-    if getattr(obj, '__code__', None):
-        return asyncio.iscoroutinefunction(obj) or inspect.isawaitable(obj)
-    else:
+    if _is_instance_mock(obj) and not isinstance(obj, AsyncMock):
         return False
+    return asyncio.iscoroutinefunction(obj) or inspect.isawaitable(obj)
 
 
 def _is_async_func(func):

mock/tests/testasync.py

diff --git a/mock/tests/testasync.py b/mock/tests/testasync.py
index 9e0d322..e6f923e 100644
--- a/mock/tests/testasync.py
+++ b/mock/tests/testasync.py
@@ -31,6 +31,10 @@
     def normal_method(self):
         pass
 
+class AwaitableClass:
+    def __await__(self):
+        yield
+
 async def async_func():
     pass
 
@@ -173,6 +177,10 @@
         with self.assertRaises(RuntimeError):
             create_autospec(async_func, instance=True)
 
+    def test_create_autospec_awaitable_class(self):
+        awaitable_mock = create_autospec(spec=AwaitableClass())
+        self.assertIsInstance(create_autospec(awaitable_mock), AsyncMock)
+
     def test_create_autospec(self):
         spec = create_autospec(async_func_args)
         awaitable = spec(1, 2, c=3)
@@ -334,6 +342,13 @@
         self.assertIsInstance(mock.normal_method, MagicMock)
         self.assertIsInstance(mock, MagicMock)
 
+    def test_magicmock_lambda_spec(self):
+        mock_obj = MagicMock()
+        mock_obj.mock_func = MagicMock(spec=lambda x: x)
+
+        with patch.object(mock_obj, "mock_func") as cm:
+            self.assertIsInstance(cm, MagicMock)
+
 
 class AsyncArguments(unittest.TestCase):
     def test_add_return_value(self):