udpate rails回调测试失败后

我有一个 :after_update 钩子在订单状态更改时发送电子邮件。它似乎无法通过以下测试,因为 :order_status_id_chaned? 返回值为false。

测试:

context 'when the order_status changes' do
  it 'should send an email' do
    @order2.save
    expect(subject).to receive(:send_confirmation_email)
    @order2.update(order_status_id: 2)
  end
end

Order.rb

class Order < ApplicationRecord
  after_update :send_confirmation_email, if: :order_just_submitted? 

  def order_just_submitted?
    p self.order_status_id_changed? # prints false
    p self.is_submitted? # prints true
    self.order_status_id_changed? and self.is_submitted?
  end

  def send_confirmation_email
    ...
  end
end

知道为什么吗 :订单\状态\标识\更改? 更新值后是否返回false?