Use basestring instead of (str, str8) to test whether

cls is a module *name*.

Lib/test/test_support.py

@@ -534,7 +534,7 @@ def run_unittest(*classes):
     valid_types = (unittest.TestSuite, unittest.TestCase)
     suite = unittest.TestSuite()
     for cls in classes:
-        if isinstance(cls, (str, str8)):
+        if isinstance(cls, basestring):
             if cls in sys.modules:
                 suite.addTest(unittest.findTestCases(sys.modules[cls]))
             else: