Router::defaultRouteClass PHP Method

    public static function defaultRouteClass($routeClass = null)
    {
        if ($routeClass === null) {
            return static::$_routeClass;
        }
        static::$_routeClass = static::_validateRouteClass($routeClass);
    }

 /**
  * Test that class must exist
  *
  * @expectedException RouterException
  * @return void
  */
 public function testSettingNonExistentDefaultRouteException()
 {
     Router::defaultRouteClass('NonExistentClass');
 }