RFC: Additional functionality for PyUnit

[MikeK]

Here's a proposed change to unittest.py that I'd like your comments
on.

I've found unit testing with PyUnit to be invaluable.  I've gotten to
the point where writing any Python code without unit tests seems,
well, perverse.  :)  But there's an inadequacy in PyUnit I keep
running into that I'd like addressed.

I often work with code that requires a large amount of work to set up
a test for, and the setup code takes an appreciable amount of time to
run.  Often, several tests that are grouped into a test case all
require a common setup.  Now, PyUnit provides us with setUp() and
tearDown() methods that we can define for each test case, which is
good.  The setup() method is run prior to EACH test method of a test
case, and the tearDown() method is run after EACH test method of a
test case.  However, when you have several test methods defined in a
test case, that all need a common setup for the tests, and the setup
is both work and time intensive, what you really want is to have a
different and additional set of setup and teardown code that is only
run ONCE for the test case.

This would let me run the difficult and long-running setup for a
series of related tests once.  It would really make unit testing my
code more doable.