die "reason";
# versus just
die;
##</code><code>##

{
   package Maths;
   sub factorial { my $n = int(pop); return $n if $n<2; $n * factorial($n - 1) }
}

use Test::More;
my @expected = qw/ 0 1 2 6 24 100 720 /;
plan tests => scalar @expected;
is(Maths::factorial($_), $expected[$_], "Factorial of $_") for 0 .. $#expected;

##</code><code>##

{
	package Maths;
	sub factorial {
		my $n = int(shift);
		die "does not compute" if $n<0;
		return $n if $n<2;
		$n * factorial($n - 1);
	}
}

use Test::More;
use Test::Exception;

my @results = qw/ 0 1 2 6 24 120 720 /;
for (0 .. $#results)
{
	lives_and { is Maths::factorial($_), $results[$_] } "Factorial of $_";
}

dies_ok { Maths::factorial(-2) } "Factorial of negative number";

done_testing;