When /^I expect to click "([^"]*)" on a confirmation box saying "([^"]*)"$/ do |option, message|
  retval = (option == 'OK') ? 'true' : 'false'
  page.evaluate_script("window.confirm = function (msg) {
    document.cookie = msg
    return #{retval}
  }")
  @expected_message = message.gsub("\\n", "\n")
end

When /^the confirmation box should have been displayed$/ do
  assert page.evaluate_script('document.cookie').include?(@expected_message),
         "Expected confirm box with message: '#{@expected_message}'" +
         "                              got: '#{page.evaluate_script('document.cookie')}'"
end