> As you pointed out in another comment, test/unit seems to be a thin shim over minitest now.

Well, that depends on if we're talking about stdlib test/unit or the test-unit gem, and also what version of ruby if we're talking about stdlib test/unit.  Starting with ruby 1.9, test/unit in the stdlib is a shim over minitest.  On 1.8 it's not, and there's also a test/unit gem that has continued to be developed that works on ruby 1.9+ that has no relation to minitest.