dont run user handlers on grpc threadpool threads
diff --git a/src/csharp/tests.json b/src/csharp/tests.json
index bc6adbb..7841051 100644
--- a/src/csharp/tests.json
+++ b/src/csharp/tests.json
@@ -31,6 +31,7 @@
     "Grpc.Core.Tests.ShutdownHookPendingCallTest",
     "Grpc.Core.Tests.ShutdownHookServerTest",
     "Grpc.Core.Tests.ShutdownTest",
+    "Grpc.Core.Tests.ThreadingModelTest",
     "Grpc.Core.Tests.TimeoutsTest",
     "Grpc.Core.Tests.UserAgentStringTest"
   ],