I think that if you already have complete hardware and electronics that will move all 3 axes to the endstops, you'll find the existing Stepper Exerciser dialog in the Reprap host code works fine for that level of overall system testing; moving each axis, homing each axis, etc. If you aren't there yet with hardware (like me -- no robot hardware, just electronics!), the test instructions for each board on the Wiki are reasonably thorough already, though more people than anyone would like seem to encounter wiring or other odd issues at Test 3 of the UCB tests, for reasons that are not entirely clear.
And for those who understand the SNAP protocol (or who want to learn more about it), the poke command lets you test (or do) anything you can send the SNAP commands to do :-) So far its main use has been just "can I actually talk to my UCBs?", but it can do a *lot* more than that if it would be useful. There is the "dance.sh" script in Subversion as a (slightly silly?) example of how it can be wrapped in a shell script.
Personally, I'd like to see (a) poke ported to Windows (b) perhaps additional shell script wrappers around poke for more testing. With Cygwin, Windows users can run such shell scripts too. Or (ugh) they could be re-written as BAT files :-)
Is there really significant value to the project in writing another piece of test software from scratch? In what ways would it be more useful than the combination of poke and the Stepper Exerciser? Which common problems would it be able to diagnose that the current approach cannot? Do you have any design docs for your tester code that you are willing to share?
If you're writing new tester code for fun and for your own education, cool, ignore me and go for it! I suspect that porting (or maybe recoding in Java, or Perl or Python or any open source interpreted language widely available on Windows/Linux/OS X) poke, and then using it as a basis for more complex tests or a prettier interface to testing, if such are needed, might be more valuable to the whole community, though, than starting over.
Jonathan
Jonathan