Failed to open stream: No such file or directory, yes there is!

Change

set_include_path(dirname(__FILE__));
require '../test2.php';

to

set_include_path(dirname(__FILE__)."/../");
require 'test2.php';

It could be a symlinks issue? Try:

set_include_path(realpath(dirname(__FILE__))); // added realpath here

Also try:

require(dirname(__FILE__) . '/../test2.php');