here is a (small but growing) BASIC65 test suite:
Bit Shifter & me are currently using this to find & narrow down bugs in the BASIC65 interpreter. It would greatly benefit from more tests covering more of BASIC65's various aspects.
So, if you're feeling like adding some tests, the suite is easy to extend. Simply save a test routine with the filename T@@@-TESTNAME (where "@@@" is a three-digit decimal number) onto the test disc and make sure that your test routine ends with DLOAD "RUNNER" (or breaks in case of an error or unexpected result). If in doubt, have a look at the existing tests for examples.
To run the test suite, simply BOOT the disc. Tests are being run in the order of their numeric ID.
If you have written any cool (or boring ;)) new tests, feel free to send them to me, so that I can add them to the disc image.