pudb has no test suite

I really love pudb. I use it multiple times a day. It has a few bugs which prevent me from recommending it wholeheartedly to my colleagues. I'd prefer to fix these myself, and send you a pull request, but the first step of my process is to add a failing test.

I see no way to do this with the current code base. Will you please add a test suite with demonstrates at least a couple basic features of pudb? I highly recommend py.test as a test runner. See my own [RefactorLib](https://github.com/bukzor/refactorlib) for an example of how to set up with py.test and integrate with setuptools.

If there does exist a test system, please show me and you may close this ticket.

Start by inspecting the current pudb codebase to confirm whether any test system already exists. If none exists, use pytest to establish a suite covering at least a couple of basic pudb features; done means the tests run successfully and provide failing-test coverage for future bug fixes.

Written by the indexing model from the issue text.