assert is class

2 files changed, 4 insertions, 2 deletions

diff --git a/psutil/tests/__init__.py b/psutil/tests/__init__.py
index b864d475..f831d6d3 100644
--- a/psutil/tests/__init__.py
+++ b/psutil/tests/__init__.py
@@ -15,6 +15,7 @@ import ctypes
 import errno
 import functools
 import gc
+import inspect
 import os
 import random
 import re
@@ -803,7 +804,8 @@ def serialtest(klass):
     class' unit tests will be run serially (1 process).
     """
     # assert issubclass(klass, unittest.TestCase), klass
-    klass._serialtest = True
+    assert inspect.isclass(klass), klass
+    klass.__serialtest = True
     return klass
 
 
diff --git a/psutil/tests/runner.py b/psutil/tests/runner.py
index 181168cf..329819ea 100755
--- a/psutil/tests/runner.py
+++ b/psutil/tests/runner.py
@@ -128,7 +128,7 @@ class _Runner:
         parallel = unittest.TestSuite()
         for obj in self._iter_testmod_classes():
             test = loadTestsFromTestCase(obj)
-            if getattr(obj, '_serialtest', False):
+            if getattr(obj, '__serialtest', False):
                 serial.addTest(test)
             else:
                 parallel.addTest(test)