Session, route and middleware

Hello, I try to display a current session in roads . It seems that the sessions are not yet established at this point . So I thought beforeMiddleware use , but it is not working .

I did :

use Closure;

class BeforeMiddleware implements Middleware {

    public function handle($request, Closure $next)
    {
        dd('test');

        return $next($request);
    }
}

Kernel :
protected $middlewareGroups = [
        'web' => [
            \App\Http\Middleware\BeforeMiddleware::class,

Route :

Route::group(['middleware' => ['web']], function () {
    dd(Session::get('locale'));

Thank you for your help.