Laravel身份验证无法在嵌套控制器上识别

I have a test controller as below:

namespace App\Http\Controllers\Modules\Test;

use App\Http\Requests;
use Illuminate\Http\Request;
use Auth;
use App\Http\Controllers\Controller;

class TestController extends Controller{
     public function __construct(){
           $this->middleware('auth');
     }

     public function index(){
           return 'testing from controller';
     }
}

When I try to access the index method via router, it bounces back as un-authenticated user! although I am already logged in. But it does not recognise as the user is already logged in. It's behave like user has not been authenticated!

Any suggestions what wrong I am doing?

I have tried with middleware group as below:

Route::group(
    ['middleware' => 'auth'],
    function () {
        Route::get('testing', 'App\Http\Controllers\Modules\Test\TestController@index');
    }
);

Result is same!!!

Any suggestions what wrong I am doing?

Any help will be much appreciated...