# File lib/mechanize/http/agent.rb, line 504
  def request_auth request, uri
    base_uri = uri + '/'
    schemes = @authenticate_methods[base_uri]

    if realm = schemes[:digest].find { |r| r.uri == base_uri } then
      request_auth_digest request, uri, realm, base_uri, false
    elsif realm = schemes[:iis_digest].find { |r| r.uri == base_uri } then
      request_auth_digest request, uri, realm, base_uri, true
    elsif realm = schemes[:basic].find { |r| r.uri == base_uri } then
      user, password, = @auth_store.credentials_for uri, realm.realm
      request.basic_auth user, password
    end
  end