diff -r 4617b7ac302a Lib/test/test_bufio.py
--- a/Lib/test/test_bufio.py	Tue Jan 08 11:27:18 2013 +0000
+++ b/Lib/test/test_bufio.py	Tue Jan 08 15:44:36 2013 -0600
@@ -11,7 +11,7 @@
 lengths = list(range(1, 257)) + [512, 1000, 1024, 2048, 4096, 8192, 10000,
                                  16384, 32768, 65536, 1000000]
 
-class BufferSizeTest(unittest.TestCase):
+class BufferSizeTest:
     def try_one(self, s):
         # Write s + "\n" + s to file, then open it and ensure that successive
         # .readline()s deliver what we wrote.
@@ -62,10 +62,10 @@
         self.drive_one(bytes(1000))
 
 
-class CBufferSizeTest(BufferSizeTest):
+class CBufferSizeTest(BufferSizeTest, unittest.TestCase):
     open = io.open
 
-class PyBufferSizeTest(BufferSizeTest):
+class PyBufferSizeTest(BufferSizeTest, unittest.TestCase):
     open = staticmethod(pyio.open)