As the community (apparently) strongly favors "doctest" over "unittest", I wrote my first test based on "zope.testing.doctest". And promptly, I was badly surprised.... In order to analyse a difficult problem, I added "from dm.pdb import zpdb; zpdb.set_trace()" in the doctest ("dm.pdb.zpdb" is my Zope aware PDB extension) -- and got a "TypeError: set_trace requires at least one argument, 0 given". Now, I know the "zpdb.set_trace()" does not want any arguments. I moved the line from the doctest code into the failing infrastructure code -- same "TypeError". I called "help(zpdb.set_trace)" and got: Help on function set_trace in module zope.testing.doctest: set_trace(self) Apparently, "doctest" has overridden "zpdb.set_trace" in an incompatible way.... I will rewrite my test as "unittest" and probably avoid in the future "zope.testing.doctest" whenever possible. -- Dieter