WIP.
diff --git a/python/minimal_test.py b/python/minimal_test.py
index 072250a..13f1124 100644
--- a/python/minimal_test.py
+++ b/python/minimal_test.py
@@ -50,6 +50,8 @@
         # system.
         self.assertTrue(_message._IS_UPB)
 
+TestMessageExtension.test_descriptor_pool.__unittest_expecting_failure__ = True
+
 
 if __name__ == '__main__':
-    unittest.main()
+    unittest.main(verbosity=2)