{ # add_trace() trivial
   
    _reset();
   
    my $ret = $error->add_trace();
    is ( $ret, 0, "add_trace() returns success (0) when successful" );
}

{ # add_trace() type
   
    _reset();
   
    $error->add_trace();
    my $type = reftype $error->stack();
    is ( $type, 'ARRAY', "Error's stack trace is an array ref upon success" );
}