# TestRole role:
package TestRole;
use Moose::Role;
requires 'test_method';
1;

# Consumer class:
package Consumer;
use Moose;
with 'TestRole';
has 'test_attribute' => (
    traits => ['Array'],
    is => 'rw',
    isa => 'ArrayRef[Str]',
    default => sub { [] },
    handles => {
        test_method => 'elements',
        add_something => 'push',
    },
);
1;

# tester.pl:
use Data::Dumper;
use Consumer;
my $c = Consumer->new();
$c->add_something("123");
my @arr = $c->test_method();
print Dumper(\@arr) . "\n";

##</code><code>##

'TestRole' requires the method 'test_method' to be implemented by 'Consumer'

##</code><code>##

    handles => {
        test_method => 'elements',
        add_something => 'push',
    },

##</code><code>##

sub add_something {
   my ($self, %args) = @_;
   # manually push here...
}
sub test_method {
   # add the 'elements' code here.
}