If you are using python2.7 or above you can use the ability of assertRaises to be use as a context manager and do:
with self.assertRaises(TypeError):
self.testListNone[:1]
If you are using python2.6 another way beside the one given until now is to use unittest2 which is a back port of unittest new feature to python2.6, and you can make it work using the code above.
N.B: I’m a big fan of the new feature (SkipTest, test discovery …) of unittest so I intend to use unittest2 as much as I can. I advise to do the same because there is a lot more than what unittest come with in python2.6 <.