I'm working on a large-ish project. I currently have some functional tests hacked together in shell scripts. They work, but I'd like to make them a little bit more complicated. I think it will be painful to do in bash, but easy in a full-blown scripting language. The target language of the project is not appropriate for implementing the tests.
I'm the only person who will be working on my branch for the foreseeable future, so it isn't a huge deal if my tests don't work for others. But I'd like to avoid committing code that's going to be useless to people working on this project in the future. 
In terms of test harness "just working" for the largest number of current and future contributors to this project as possible, am I better off porting my shell scripts to Python or Perl? 
I suspect Perl, since I know that the default version of Python installed (if any) varies widely across OSes, but I'm not sure if that's just because I'm less familiar with Perl.
This is more personal, but I always used python and will use it till something shows me it's better to use other. Its simple, very expansible, strong and fast and supported by a lot of users. 
The version of python doesn't matter much since you can update it and most OSes have python 2.5 with expands the compatibility a lot. Perl is also included in Linux and Mac OS, though.
I think that Python will be good, but if you like perl and have always worked with it, just use perl and don't complicate your life.
Python vs Perl for portability?