in reply to Grouping tests

This is where Test-Harness's 'prove' command-line tool shines, you can specify exactly which tests you want to run. From the doco:
* prove is granular prove lets your run against only the files you want to check. Running "prove t/live/ t/master.t" checks every *.t in t/live, plus t/master.t.
Check out the -r option as well.