Route::any('/', function () {
    return Redirect::getUrlGenerator()->getRequest()->headers->get('referer');
});

Route::get('/test',function (){
   return Redirect::back();
});

class Redirector
{

    /**
     * Create a new Redirector instance.
     *
     * @param  \Illuminate\Routing\UrlGenerator  $generator
     * @return void
     */
    public function __construct(UrlGenerator $generator)
    {
        $this->generator = $generator;
    }

 /**
     * Create a new redirect response to the previous location.
     *
     * @param  int  $status
     * @param  array  $headers
     * @param  mixed  $fallback
     * @return \Illuminate\Http\RedirectResponse
     */
    public function back($status = 302, $headers = [], $fallback = false)
    {
        return $this->createRedirect($this->generator->previous($fallback), $status, $headers);
    }

...