This directory should at some point contain lots of fancy unit (and 
not-so-unit) tests.

There are two kinds of unittests in here:

*test.py -- tests for python's plain unittest framework
test_*.py -- tests for twisted's trail framework (i.e., tests needing a
  reactor).  One could probably use trial for the unittest tests as well.


In addition, runAllTests guesses what modules might contain unittests and
adds them to its test suite as well.