This causes the harness to pause to wait on a list of tests before starting the one containing the wait attribute.
This causes the entire run to be aborted if the process containing the haltfail attribute fails, forcibly killing all remaining processes and exiting the harness. Thus, the testbed drops into forensic state for debugging.
Perl System Test (PEST) is a test harness, written in Perl, for running processes on a distributed testbed via SSH. It's available for free on Sourceforge: