Ruter MinSide Ruby wrapper for retrieving travel card information

ruter.rb

# encoding: utf-8
require 'mechanize'

class Ruter
  class NotLoggedInError < StandardError; end

  def self.log_in(username, password)
    agent = Mechanize.new
    agent.ca_file = '/usr/lib/ssl/certs/ca-certificates.crt'

    page = agent.get('https://www2.ruter.no/minside/logg-inn/')

    form = page.form_with(:action => '/minside/logg-inn/')

    form.field_with(:name => /UserName$/).value = username
    form.field_with(:name => /Password$/).value = password

    submit = form.button_with(:value => "Logg inn")

    @@page = form.click_button(submit)
  end  

  def self.get_cards
    throw NotLoggedInError.new unless defined?(@@page)

    cards = @@page.search('.travelCard:not(.travelCardBlocked)')

    cards.map do |card|
      {
        serial: (card / 'h3:contains("Kortnummer") ~ span').text.strip,
        name: (card / 'h2').text.strip,
        expiry: (card / 'table td:contains("Utløper") ~ td').text.strip
      }
    end
  end
end