class ActionDispatch::Routing::RouteSet::Generator

def normalize_options!
  # If an explicit :controller was given, always make :action explicit
  # too, so that action expiry works as expected for things like
  #
  #   generate({:controller => 'content'}, {:controller => 'content', :action => 'show'})
  #
  # (the above is from the unit tests). In the above case, because the
  # controller was explicitly given, but no action, the action is implied to
  # be "index", not the recalled action of "show".
  if options[:controller]
    options[:action]     ||= 'index'
    options[:controller]   = options[:controller].to_s
  end
  if options[:action]
    options[:action] = options[:action].to_s
  end
end