How do you test code that uses subroutines (sub)?

Testing code that uses subroutines in Perl can be accomplished using various testing frameworks, with the most common being 'Test::More'. Below is an example that demonstrates how to test a subroutine in Perl.


        #!/usr/bin/perl
        use strict;
        use warnings;
        use Test::More;

        # Sample subroutine
        sub add {
            my ($a, $b) = @_;
            return $a + $b;
        }

        # Testing the subroutine
        is(add(1, 2), 3, 'Adding 1 and 2 should return 3');
        is(add(2, 3), 5, 'Adding 2 and 3 should return 5');
        is(add(-1, 1), 0, 'Adding -1 and 1 should return 0');

        done_testing();