cant set session $this->session->userdata

[yaldi4]

hey, i want to make a test on a protected method of a controller
the test:

<?php
require_once '../../application/libraries/Backend_controller.php';
class Welcome_test extends TestCase
{
	public function test_index()
	{
		$output = $this->request('GET', 'ticket/edit');
		printr($output);die;
	}
}

the $output returns null.
the ticket controllers extends backend_controller
the backen_controller:

<?php
if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
* Class Backend_Controller
*/
class Backend_controller extends CORE_controller
{
	function __construct()
	{
		parent::__construct();
		$this->load->model('user/user_m');
		$this->load->model('setting/setting_m');
		$this->load->model('localisation/language_m');
		$this->load->model('vcounter/vcounter_m');

		// Login check
		$exception_uris = array(
			'user/login',
			'user/logout',
			'user/register',
			'verification/email/',
			'verification/test',
			'user/forgotten',
			'user/reset_password',
		);

		if (in_array(uri_string(), $exception_uris) == FALSE) {
			if ($this->user_m->loggedin() == FALSE) {
				// $redirect = current_url();
				redirect(base_url('/user/login').'?url='.uri_string());
			}
		}
        }
       public function validate_modify($controller = NULL) {
           if ($this->user_m->hasPermission('modify', $controller) === TRUE) {
        	return TRUE;
           }

           $this->session->set_flashdata('error', lang('error_permission'));
             return FALSE;
      }
}

when i add 'ticket/edit' to $exception_uris.
the error is: RuntimeException : Trying to access array offset on value of type null on line 189 in file C:\laragon\www\new-smart\application\models\user\User_m.php
│
│ C:\laragon\www\new-smart\application\tests_ci_phpunit_test\CIPHPUnitTestCase.php:184
│ C:\laragon\www\new-smart\application\models\user\User_m.php:189
│ C:\laragon\www\new-smart\application\libraries\Backend_controller.php:82

user_m snippet:

public function hasPermission($key = NULL, $controller = NULL)
	{
		$this->load->model('user/user_permission_m');
		$permissions = NULL;
		
		foreach (unserialize($this->session->userdata['user_group_id']) as $user_group_id) {
			$where = array(
				'user_group_id' => $user_group_id
			);
			$result = $this->user_permission_m->get_by($where, TRUE);
			if (is_array(unserialize($result['permission']))) {
				$permissions = unserialize($result['permission']);
			}

			if (is_array($permissions[$key])) {
				if (in_array($controller, $permissions[$key])) {
					return TRUE;
				}
			}
		}

		return FALSE;
	}

the ticket snippet:

<?php
if (!defined('BASEPATH')) exit('No direct script access allowed');
class Ticket extends Backend_controller {

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

   public function edit($id = NULL)
    {
        // Load the view
        if ($this->validate_modify('Ticket')) {
            $this->data['subview'] = 'backend/ticket/edit';
        } else {
            $this->session->set_flashdata('error', lang('error_permission'));
            $this->data['subview'] = 'backend/common/error';
        }
        $this->load->view('backend/_layout_main', $this->data);
    }
}

it seems the backend_controller cant get access to $this->session->userdata.
how do i set the $this->session->userdata in my test so i can access my protected controller?

[kenjis]

What is $this->session->userdata['user_group_id']?

As far as I know, $this->session->userdata() is a method, not an array.
https://codeigniter.com/userguide3/libraries/sessions.html#retrieving-session-data

hey, i want to make a test on a protected method of a controller

I don't get what is a protected method you say.

You do not need to test protect methods in general.
A protect method is tested within a test on public methods.