package MyModule;

use strict;
use warnings;

sub add {
    my ($left, $right) = @_;
    return $left + $right;
}

1;

__END__

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

# we have 3 tests to run
use Test::More tests => 3;
# if you dont know how many tests
# you have you can just replace:
#   tests => 3
# with:
#   "no_plan"
# that way you dont have to count 
# your tests, although when you are 
# finished its best to put the plan back 
# in place.

# test that we can require the module
require_ok("MyModule.pm");
# it also has the added benefit of requiring
# the actual module

# test that the module has the function "add" available
can_ok("MyModule", 'add');

# now test "add" works as expected
cmp_ok(MyModule::add(1, 1), '==', 2, '... 1 added to 1 is 2');


##</code><code>##

prove test.t

##</code><code>##

test....ok                                                                   
All tests successful.
Files=1, Tests=3,  0 wallclock secs ( 0.15 cusr +  0.05 csys =  0.20 CPU)