From f3a9d722d77753f5110e35f46bd61732c0cb81c1 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Sat, 13 Apr 2019 12:31:58 -0700
Subject: [PATCH] bpo-36593: Fix isinstance check for Mock objects with spec
 executed under tracing (GH-12790)

In Python having a trace function in effect while mock is imported causes isinstance to be wrong for MagicMocks. This is due to the usage of super() in some class methods, as this sets the __class__ attribute. To avoid this, as a workaround, alias the usage of super .
(cherry picked from commit 830b43d03cc47a27a22a50d777f23c8e60820867)

Co-authored-by: Xtreak <tir.karthi@gmail.com>
---
 Lib/unittest/mock.py                          |  2 +-
 Lib/unittest/test/testmock/testmock.py        | 38 +++++++++++++++++++
 .../2019-04-11-22-11-24.bpo-36598.hfzDUl.rst  |  2 +
 3 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2019-04-11-22-11-24.bpo-36598.hfzDUl.rst

diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 5b8e74414035..373e1d5f64d8 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -738,7 +738,7 @@ class NonCallableMock(Base):
 
         obj = self._mock_children.get(name, _missing)
         if name in self.__dict__:
-            super().__delattr__(name)
+            _safe_super(NonCallableMock, self).__delattr__(name)
         elif obj is _deleted:
             raise AttributeError(name)
         if obj is not _missing:
diff --git a/Lib/unittest/test/testmock/testmock.py b/Lib/unittest/test/testmock/testmock.py
index 447a502b57d6..2f50236d1ece 100644
--- a/Lib/unittest/test/testmock/testmock.py
+++ b/Lib/unittest/test/testmock/testmock.py
@@ -1811,6 +1811,44 @@ class MockTest(unittest.TestCase):
         self.assertRaises(TypeError, mock.child, 1)
         self.assertEqual(mock.mock_calls, [call.child(1, 2)])
 
+    def test_isinstance_under_settrace(self):
+        # bpo-36593 : __class__ is not set for a class that has __class__
+        # property defined when it's used with sys.settrace(trace) set.
+        # Delete the module to force reimport with tracing function set
+        # restore the old reference later since there are other tests that are
+        # dependent on unittest.mock.patch. In testpatch.PatchTest
+        # test_patch_dict_test_prefix and test_patch_test_prefix not restoring
+        # causes the objects patched to go out of sync
+
+        old_patch = unittest.mock.patch
+
+        # Directly using __setattr__ on unittest.mock causes current imported
+        # reference to be updated. Use a lambda so that during cleanup the
+        # re-imported new reference is updated.
+        self.addCleanup(lambda patch: setattr(unittest.mock, 'patch', patch),
+                        old_patch)
+
+        with patch.dict('sys.modules'):
+            del sys.modules['unittest.mock']
+
+            def trace(frame, event, arg):
+                return trace
+
+            sys.settrace(trace)
+            self.addCleanup(sys.settrace, None)
+
+            from unittest.mock import (
+                Mock, MagicMock, NonCallableMock, NonCallableMagicMock
+            )
+
+            mocks = [
+                Mock, MagicMock, NonCallableMock, NonCallableMagicMock
+            ]
+
+            for mock in mocks:
+                obj = mock(spec=Something)
+                self.assertIsInstance(obj, Something)
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2019-04-11-22-11-24.bpo-36598.hfzDUl.rst b/Misc/NEWS.d/next/Library/2019-04-11-22-11-24.bpo-36598.hfzDUl.rst
new file mode 100644
index 000000000000..2a7980209136
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-04-11-22-11-24.bpo-36598.hfzDUl.rst
@@ -0,0 +1,2 @@
+Fix ``isinstance`` check for Mock objects with spec when the code is
+executed under tracing. Patch by Karthikeyan Singaravelan.
-- 
2.47.3