With a larger amount of tests, each one can be given a little descriptive name as the second argument to ok().
use Test::Simple tests => 2;
ok(defined $ical, 'new() returned something'); # checking we have something
ok($ical->isa('Date::ICal'), " and it's the right class" ); # checking its the right class
# the above prints:
1..2
ok 1 - new() returned something
ok 2 - and it's the right class