use strict;
use warnings;
use User::pwent;    # overrides normal getpwent()
use Test::More 'no_plan';

# Duplicate UIDs
my @dups = duplicate_uids();
is( @dups, 0, "duplicate uids (@dups)" );

sub duplicate_uids {
    my @uids;
    while ( my $pwent = getpwent() ) {
        push @uids, $pwent->uid;
    }
    endpwent();
    my %seen = ();
    my @dups = grep { $seen{$_}++ } @uids;
    if (@dups) {
        return @dups;
    } else {
        return 0;
    }
}