Rename class attribute containing the class to be tested, so the name is the
same as for the string and sequence tests.
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index 1e283cd..4cdc29d 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -209,7 +209,7 @@
 
 class EnvironTests(mapping_tests.BasicTestMappingProtocol):
     """check that os.environ object conform to mapping protocol"""
-    _tested_class = None
+    type2test = None
     def _reference(self):
         return {"KEY1":"VALUE1", "KEY2":"VALUE2", "KEY3":"VALUE3"}
     def _empty_mapping(self):