lives_ok {
    close  $fh  or die "closing '$f': $!";
    close  $wfh or die "closing '$wf': $!";
    unlink $wf  or die "unlinking '$wf': $!";
    } 
    'file cleanup ok';
dies_ok {
    open my $wfh, '<', $wf or die "opening '$wf': $!";
    }
    "after unlink of '$wf': cannot re-open for read";