How to run tests without installing?

How can I run the regression tests on my work-in-progress without
installing it first?

Say I'm changing something in sh.  Can I run the tests on the
compiled sh in /usr/obj, without having to install my potentially
broken work into the system?  Running "make tests" in src/bin/sh
doesn't seem to actually test anything.

-- 
Christian "naddy" Weisgerber                          naddy@mips.inka.de