"finally" for unit test

[killkolor]

hi!

I have a unittest framework that tests a single function that in turn
works with files (takes input and outputs in the same file, no return
values).
In the unittest class I assign a member with all the names of my
testfiles and a testdirectory. The tests call the function (which
opens and writes to the file) and then opens the file to see if
everything is in order. The problem now is that after each testrun I
have to copy "fresh" files into the testdirectory, since of course the
function already run on all the files and made the changes. So I
implemented a buffering in the unittest functions: buffer the file,
call the function, make the test, write the buffered file back. This
works fine for unittests that do not fail. If a unittest fails though
the function stops and the writing back is never done. Is there
something like a finally for unittest functions? Or could I use
another approach to buffer and write back my files (for each unittest
function)?
thanks!
gabriel