How to avoid reloading instances which have been change by another model

[Gustavo Caso]

This is my product_spec.rb

describe Product do

  before(:each) do

    @sale = Sale.create

    @product = @sale.products.build

    @product.should be_valid

  end

  describe "price, quote, tax" do

    before(:each) do

      @product.price = 121

      @product.price_before_discount = 200

      @sale.tax_rate.should eq(21)

    end

    describe "integration with sale" do

      

      it "should update sale upon saving" do

        @sale.product_price.should eq(0.0)

        @product.save.should be_true

        @sale.reload

        @sale.product_price.should eq(121)

      end

      

      it "should not affect the previous product_price" do

        @product1 = @sale.products.create(price: 100)

        @sale.reload

        @sale.product_price.should eq(100)

        @product2 = @sale.products.create(price: 100)

        @sale.reload

        @sale.product_price.should eq(200)

        

        @product.save

        @sale.reload

        @sale.product_price.should eq(321)

      end

    end

  end

end

This is product.rb

class Product < ActiveRecord::Base

  

  after_create :update_sale_product_price

  

  belongs_to :sale

  validates_presence_of :sale

 

  

  def update_sale_product_price

    sale.reload

    sale.product_price += price

    sale.save

  end

end

All the test are passing, but I would like to know if there is way to avoid reloading the the instance variable  or how to deal with this kind of situations, is mock_model or stub_model  or mocking methods the solution, because as you can see I need to reload even in the model.

Thanks