$ prove foo.t
foo......1/? [WARN] 2008/04/02 11:26:41 main::add foo.pl:20 - possible overflow
foo......ok
All tests successful.
Files=1, Tests=8,  1 wallclock secs ( 0.01 usr  0.00 sys +  0.08 cusr  0.01 csys =  0.10 CPU)
Result: PASS