package Foo;
use warnings;
use strict;

sub new {
    return bless {}, $_[0];
}
sub blah {
    my ($self, $args) = @_;

    my $method = 'process';

    my $updated = $self->$method($args);

    return $updated;
}
sub process {
    my ($self, $args) = @_;

    my @updated;

    push @updated, $_ * 2 for @$args;
    
    return \@updated;
}

package main;

my $obj = Foo->new;

my $method = 'blah';
my $args = [qw(1 2 3)];

my $return = $obj->$method($args);

print "$_\n" for @$return;


##</code><code>##

spek@scelia ~/scratch $ perl obj.pl 
2
4
6

##</code><code>##

# test A
{
    my $object = Some::Package::Name->new;
    is $object->some_method_name($y), 1, "some_method_name() with arg $y ok";
    ...
}

# test B
{
    my $object = Some::Package::Name->new;
    is $object->some_method_name($z), 2, "some_method_name() with arg $z ok";
    ...
}

...

##</code><code>##

...

my $mod = 'Some::Package::Name';
my $m   = 'method_tested_in_this_test_file';

# testA
{
    my $o = $mod->new;
    is $o->$m($arg), 1, "return val of $m with arg $arg ok";
    ...
}

# testB
{
    my $o = $mod->new;
    is eval {$o->$m('blah'); 1}, undef, "$m croaks if sent in 'blah'";
    like $@, qr/idiot!/, "...and error message is sane";
    ...
}

...