The Perl community has already created several implementations of the above mentioned ok() function. We'll go with the one in the module called Test::Simple. Not only will that print "ok" or "not ok" but it will also include a counter. In order to use it first we'll need to declare how many test units are we planning to call, that is, how many times are we planning to call the ok() function. In return we get extra features such as printing the line numbers of the ok() calls that failed and getting a final report on the number of failed tests out of the planned tests. use Test::Simple, tell it your plan, that is the number of times you are going to call ok() and use its built in ok() function.

examples/perl/tests/t10.pl
use strict;
use warnings;

use FindBin;
use lib "$FindBin::Bin/../lib";
use MyTools;

use Test::Simple tests => 3;

ok( sum(1, 1)    == 2 );
ok( sum(2, 2)    == 4 );
ok( sum(2, 2, 2) == 6 );

Output:

examples/perl/tests/t10.pl.out
1..3
ok 1
ok 2
not ok 3

#   Failed test at examples/perl/tests/t10.pl line 12.
# Looks like you failed 1 test of 3.

It is more verbose, it has a couple of additional useful pieces of information: 1..3 says how many tests we were planning, then we get the tests numbered and we even get a small explanation when the test fails.