To test the board I'm using MicroPython, a nice board with a built-in Python interpreter. I picked it up off their Kickstarter a while back and I've been looking for a use for it. Coding for it was an absolute pleasure (it's Python after all); it's API is clear and concise and it does excatly what it says on the tin with no fuss.
So far I've run tests on the SRAM (the XMEGA MCU tests will need to come later when my programmer + the ROM chip arrive). I wrote a MicroPython script that performs a quick test of the data + address bus connections and then does an exhaustive test over the whole 64KB of mem. The MicroPython board supplies sufficient 3V3 current too which I use to power the CUPCake board.
The only downside to bitbanging with MicroPython is that it's sloooooow (~ 17 bytes/second so it takes ~60 s/1KB)
$ ./minicom -D /dev/ttyACM0 Testing SRAM... [+] Data bus -> OK [+] Address bus -> OK [+] 64K test -> OK DONE!
Everything works out; so far so good.