Package A;

use Carp;

sub new {
 ...
}

sub f1 {
my $param1 = shift;
my $param2 = shift;
my $param3 = shift;

croak '- parameter1 required' unless $param1;
if ((!$param2) && $param3 eq 'X') {
    croak '- parameter2 required' ;
}

some code here;
}


##</code><code>##


use Test::More qw(no_plan);

my $n = 1;
BEGIN {
	use_ok('A');
}
$n++;

my $a = new A;

isa_ok( $a,"A");
$n++;

eval {
	$a->f1( ) };

print "ok $n";
print "\t\tno arguements passed\n";
if ( $@) {
	diag ( "$@\n" );
}
$n++;