[Resolved] How Extending Controller?

[eluser]soprabaixar1[/eluser]
How Extending Controller?

test_1.php

Code:

<?php
class Test_1 extends CI_Controller {

    function __construct()
    {
        parent::__construct();
    }

    function index()
    {
        print 'welcome';
    }
}
?>

test_2.php

Code:

<?php
class Test_2 extends Test_1 {

    function __construct()
    {
        parent::Test_1();
    }
}
?>

I returned the following error:

Fatal error: Class 'Test_1' not found in ...application\controllers\test_2.php on line 2