[plt-scheme] SchemeUnit: [Listof TestSuite] -> TestSuite

I feel like I'm missing something obvious, but is there a way to form a 
test suite out of a given list of test suites?  All I see is the syntax:

    (test-suite name [#:before thunk] [#:after thunk] test ...)

In addition to the compound testing forms, there should probably be 
procedures for constructing compound tests.

David