This directory holds a great deal of test code, most of which is useless to the average user.
test/client/sysint has a collection of tests we have used when implementing (or reimplementing) various system interface functions.
test/correctness/pts holds the PVFS Test Suite (PTS), a suite designed for testing the correctness of PVFS under various different conditions. There are actually quite a few tests in here, and the vision is that we will run these in an automated fashion relatively often (but we aren't there quite yet). This is probably the second most useful code (after pvfs2-client) in the test directory.