Accessing variables defined in unit testcase file in src file using phing

[sectrait]

I have defined some variables in my test file then i call a function from my test file to src file and verify the result. While using phing it is not working, but if i use php or phpunit to verify it is working fine.

Example: add.php (source file) (present in the src directory)

<?php
function add_two_numbers()
{
    global $a,$b; /* defined in test file*/
    return ($a + $b);
}
?>
 

Other file:

// add_Test (Test File) (present in the test directory)

<?php
$a = 5;
$b = 3;
require_once ("__DIR__./../src/add.php");
 
class add_Test extends PHPUnit_Framework_TestCase{
    function testadd()
    {
        $act = 8;
        $res = add_two_numbers();
        $this -> assertTrue($res === $act);
    }
}
 
?>
 

Now, if i use phpunit then it is working file but with phing the global variables are not set. Please tell me a solution to this.