catch nasty exception classes with __new__ that doesn't return a exception (closes #11627)

Patch from Andreas Stührk.

1 files changed, 9 insertions, 0 deletions

diff --git a/Lib/test/test_raise.py b/Lib/test/test_raise.py
index d120dc1..e02c1af 100644
--- a/Lib/test/test_raise.py
+++ b/Lib/test/test_raise.py
@@ -121,6 +121,15 @@ class TestRaise(unittest.TestCase):
         else:
             self.fail("No exception raised")
 
+    def test_new_returns_invalid_instance(self):
+        # See issue #11627.
+        class MyException(Exception):
+            def __new__(cls, *args):
+                return object()
+
+        with self.assertRaises(TypeError):
+            raise MyException
+
 
 class TestCause(unittest.TestCase):
     def test_invalid_cause(self):