my %deref = %{$_[0

    my %hash_for_popup;
    my @values = @{ $deref{test1} };
    my @labels = @{ $deref{test2} };

    @hash_for_popup{ @values } = @labels;
    # ...

            
    print STDOUT $cgi -> popup_menu (
        -name    => 'fieldname',
        -values  => $deref{'test2'},
        -labels  => \%hash_for_popup
    );