I am not a fan of it, but in rare cases it is useful to know that done_testing can be used to signal all tests have been done. This way we don't need to have a "plan".

use strict;
use warnings;

use lib 'lib';
use MyTools;

use Test::More;

    my $result = sum(1, 1);
    is $result, 2,  '1+1';

    my $result = sum(2, 2);
    is $result, 4,  '2+2';