factory_bot build_stubbed strategy

Question

构建策略的factory_bot文档说:

factory_bot支持几种不同的构建策略:build、create、attributes_for和build_stub

并继续使用一些例子。然而，它并没有清楚地说明每一个的结果是什么。我用create和build已经有一段时间了。从描述来看，attributes_for似乎很简单，我看到了它的一些用途。那么，build_stubbed是什么呢?描述说

返回一个具有所有已定义属性的对象

什么是"存根"?的意思吗?这与create或build有何不同?

Answer 1

让我们考虑一下这些工厂的例子中的区别:

FactoryBot.define do
factory :post do
user
title { 'Post title' }
body { 'Post body' } 
end
end
FactoryBot.define do
factory :user do
first_name { 'John' }
last_name { 'Doe' }
end
end

构建

使用build方法一切都很容易。它返回一个没有保存的Post实例

# initialization
post = FactoryBot.build(:post)

# call
p post
p post.user

# output
#<Post:0x00007fd10f824168> {
:id => nil,
:user_id => nil,
:title => "Post title",
:body => "Post body",
:created_at => nil,
:updated_at => nil
}
#<User:0x00007f8792ed9290> {
:id => nil,
:first_name => "Post title",
:last_name => "Post body",
:created_at => nil,
:updated_at => nil
}

Post.all # => []
User.all # => []

创建

对于create，一切都很明显。它保存并返回一个Post实例。但是它调用了所有的验证和回调并创建了User

的相关实例

# initialization
post = FactoryBot.create(:post)

# call
p post
p post.user

# output
#<Post:0x00007fd10f824168> {
:id => 1,
:user_id => 1,
:title => "Post title",
:body => "Post body",
:created_at => Sat, 18 Jun 2022 05:32:17.122906000 UTC +00:00,
:updated_at => Sat, 18 Jun 2022 05:32:17.122906000 UTC +00:00
}
#<User:0x00007f8792ed9290> {
:id => 1,
:first_name => "John",
:last_name => "Joe",
:created_at => Sat, 18 Jun 2022 05:32:17.122906000 UTC +00:00,
:updated_at => Sat, 18 Jun 2022 05:32:17.122906000 UTC +00:00
}

在数据库中创建了Post记录和关联的用户记录:

Post.all # => [<Post:0x00007fd10f824168> {...}]
# User also created in the database
User.all # => [<User:0x00007f91af405b30> {...}]

build_stubbed

build_stubbed模仿创建。它简化了id,created_at,updated_at和user_id属性。它还会跳过所有的验证和回调。

存根意味着FactoryBot只是初始化对象，并给id、created_at和updated_at属性赋值，这样看起来就像创建的． 对于id，它分配整数1001(1001只是FactoryBot用来分配id的默认数字)，对于created_at和updated_at，它分配当前日期时间。并且对于使用build_stubbed创建的每个其他记录，它将使分配给id的number增加1。首先FactoryBot初始化user记录，并将1001赋值给id属性，但不将其保存到数据库;其次是初始化post记录，将1002赋值给id属性，将1001赋值给user_id属性进行关联，但也不将记录保存到数据库。

#initialization
post = FactoryBot.build_stubbed(:post)

# call
p post
p post.user

# output
# It looks like persisted instance
#<Post:0x00007fd10f824168> {
:id => 1002,
:user_id => 1001,
:title => "Post title",
:body => "Post body",
:created_at => Sat, 18 Jun 2022 05:32:17.122906000 UTC +00:00,
:updated_at => Sat, 18 Jun 2022 05:32:17.122906000 UTC +00:00
}
#<User:0x00007f8792ed9290> {
:id => 1001,
:first_name => "John",
:last_name => "Joe",
:created_at => Sat, 18 Jun 2022 05:32:17.122906000 UTC +00:00,
:updated_at => Sat, 18 Jun 2022 05:32:17.122906000 UTC +00:00
}

Post和user记录没有在数据库中创建!!

# it is not persisted in the database
Post.all # => []
# Association was also just stubbed(initialized) and there are no users in the database.
User.all # => []