xmlroff has an XSL testsuite with less than a hundred tests.
NIST produced a testsuite for XSL 1.0 CR with over a thousand tests. Several vendors also produced large testsuites.
The NIST testsuite is too large to be useful if you just want to start small.
It would be useful if there existed a stylesheet (or some other mechanism) that took the NIST testsuite.xml file and, probably, a control file then produced a HTML form or similar where you can pick tests or groups of tests you want to enable and then generated a testsuite.xml file describing only the tests you selected.
It should be possible to run it again and modify the previous selection rather than having to start again each time.
