diff --git a/python-stdlib/unittest/unittest.py b/python-stdlib/unittest/unittest.py
index 70da2ce1..deb678b9 100644
--- a/python-stdlib/unittest/unittest.py
+++ b/python-stdlib/unittest/unittest.py
@@ -29,10 +29,21 @@ class AssertRaisesContext:
         return False
 
 
+class NullContext:
+    def __enter__(self):
+        pass
+
+    def __exit__(self, a, b, c):
+        pass
+
+
 class TestCase:
     def __init__(self):
         pass
 
+    def subTest(self, msg=None, **params):
+        return NullContext()
+
     def skipTest(self, reason):
         raise SkipTest(reason)