There are two parts to running a test in Perl.
The output of your test is piped to Test::Harness.
Test::Harness interprets your output and reports.
$ perl -MTest::Harness -wle 'runtests @ARGV' contrived.t
contrived....ok
All tests successful.
Files=1, Tests=1, 0 wallclock secs ( 0.02 cusr + 0.02 csys = 0.04 CPU)