If your in test1.php.. which is under the directory one, recursively include backwards like so:
include('../../test1.php'):
or if that is the only file you are including, add this directive to the top of your page:
ini_set("include_path","/home/myhome/one/");
on Linux or on windows:
ini_set("include_path","C:/inetpub/wwwroot/myhome/one/");
then you can just use the include like so:
include('test1.php');
Have phun!