Need to write a good RSpec unit test for this small class(probably thinking about TDD&BDD first). And how could you improve this report class? Let's go :)

order_reporter.rb

class OrderReporter
  attr_reader :order
  attr_reader :report

  def initialize(order)
    @order = order
  end

  def call
    return generate_empty_report if order_items_blank?

    generate_order_report
  end

  private

  attr_writer :report

  def order_items_blank?
    order.items.blank?
  end

  def generate_empty_report
    self.report = [
      error: 'The order has no items!'
    ]
  end

  def generate_order_report
    self.report = {}

    order.items.each { |order_item| self.report[order_item.number] = generate_item_report(order_item) }

    report
  end

  def generate_item_report(order_item)
    order_item_reporter.call(order_item)
  end

  def order_item_reporter
    @order_item_reporter ||= OrderItemReporter.new
  end
end