监控进程干扰工厂的实例初始化

Question

在我的项目中，user 将有许多 items，它们的 onshelf_at 属性在创建时默认为 DateTime.now。

# item.rb
class Item < ActiveRecord::Base

  before_create :calculate_onshelf_time

  default_scope :order => 'items.onshelf_at DESC'

  def calculate_onshelf_time
    self.onshelf_at = DateTime.now
  end

end

在用户模型测试中，我试图说服自己检索到的订单确实是items.onshelf_at DESC。于是我做了下面的sn-p，结果却是反了。 （即[@item1, @item2]）

# spec/models/user_spec.rb
before :each do
  @user = User.create(@attr)
  @item1 = Factory(:item, :owner=>@user, :onshelf_at => 2.days.ago, :created_at => 2.days.ago)
  @item2 = Factory(:item, :owner=>@user, :onshelf_at => 1.day.ago, :created_at => 1.day.ago)        
end


it "should have the right items in the right order" do
  @user.items.should == [@item2, @item1]
end

我检查了控制台，发现 onshelf_at 没有监听 Factory Girl 的实例初始化。取而代之的是，它遵循 before_create 规则，并重视运行测试的时间！

Failure/Error: @user.items.should == [@item2, @item1]
   expected: [#<Item id: 2, description: "this is an item", img_link: "http://www.example.com/photos/some_pic.jpg", category_id: 5, onshelf: true, created_at: "2011-11-20 11:19:15", updated_at: "2011-11-21 11:19:15", onshelf_at: "2011-11-21 11:19:15", owner_id: 1>, #<Item id: 1, description: "this is an item", img_link: "http://www.example.com/photos/some_pic.jpg", category_id: 5, onshelf: true, created_at: "2011-11-19 11:19:15", updated_at: "2011-11-21 11:19:15", onshelf_at: "2011-11-21 11:19:15", owner_id: 1>]
        got: [#<Item id: 1, description: "this is an item", img_link: "http://www.example.com/photos/some_pic.jpg", category_id: 5, onshelf: true, created_at: "2011-11-19 11:19:15", updated_at: "2011-11-21 11:19:15", onshelf_at: "2011-11-21 11:19:15", owner_id: 1>, #<Item id: 2, description: "this is an item", img_link: "http://www.example.com/photos/some_pic.jpg", category_id: 5, onshelf: true, created_at: "2011-11-20 11:19:15", updated_at: "2011-11-21 11:19:15", onshelf_at: "2011-11-21 11:19:15", owner_id: 1>] (using ==)

我该如何解决这个问题？

Answer 1

一个快速的解决方法是为您的calculate_onshelf_time 方法添加一个条件：

 self.onshelf_at = DateTime.now if self.onshelf_at.nil?

但是 - 你甚至不需要这一切。如果可以（也就是说，如果您可以控制模式），请将 onshelf_at 属性替换为 created_at 列，该列将在创建时由 Rails 自动设置。如果您使用迁移：

 create_table :foo do |t|
   # ...
   t.timestamps
 end

将为模型添加created_at 和updated_at 时间戳。