# original idea is by @a_matsuda.
# it { should filter(:update).by :require_session }
# => should filter update by require_session

RSpec::Matchers.define :filter do |action_name|
  action_name = action_name.to_s
  match do
    callbacks = controller._process_action_callbacks.select { |c| c.kind == :before && @method_names.include?(c.filter.to_s)}

    if callbacks.count != @method_names.count || callbacks.empty?
      false
    else
      callbacks.all? do |callback|
        callback.per_key[:if].all?{|c|eval(c)} && !callback.per_key[:unless].any?{|c|eval(c)}
      end
    end
  end
  def by(*method_names)
    @method_names = method_names.map(&:to_s)
    self
  end
  description do
    "filter #{action_name} by #{@method_names.join(', ')}"
  end
  failure_message_for_should do
    "not filter #{action_name} by #{@method_names.join(', ')}"
  end
end