The py lib has several namespaces which help with automated testing, and with accessing filesystems. Here is some documentation on the core namespaces:
py.test write and deploy unit- and functional tests to multiple machines.
py.code: generate code and use advanced introspection/traceback support.
py.path: use path objects to transparently access local and svn filesystems.
py lib scripts to make python development easier.
py.xml for generating in-memory xml/html object trees
py.io: Helper Classes for Capturing of Input/Output
py.log: an alpha document about the ad-hoc logging facilities
miscellaneous features describes some small but nice py lib features.
For the latest Release, see PyPI project page