class Need1s < Entities
  attr :ok
  self.needs :Need2s

  def setup_data
    dputs(2) { 'Need1s setting up' }
    @ok = Entities.is_setup?(:Need2)
  end
end


class Need2s < Entities
  attr :ok

  def setup_data
    dputs(2) { 'Need2s setting up' }
    @ok = !Entities.is_setup?(:Need1)
  end
end