code: public function addRealm($url, $type, $realm)
      {
          $this->realms[$url->getHost()][$realm] = new SimpleRealm($type, $url);
      }
docs: Adds a new realm centered the current URL. Browsers privatey wildly on
  their behaviour in this regard. Mozilla ignores the realm and presents
  only when challenged, wasting bandwidth. IE just carries on presenting
  until a new challenge occours. SimpleTest tries to follow the spirit of
  the original standards committee and treats the base URL as the root of a
  file tree shaped realm.
  
  @param SimpleUrl $url    Base of realm.
  @param string $type      Authentication type for this realm. Only
  Basicauthentication is currently supported.
  @param string $realm     Name of realm.