唯一性验证测试的外键约束问题

Question

跑轨 4.2.8

我添加了一个foreign_key为user_id的新模型。虽然从功能上一切似乎都很好，但当我运行测试确认user_id的唯一性验证时，我得到了一个ActiveRecord::InvalidForeignKey错误。详情如下。

迁移

create_table :standard_accounts do |t|
t.timestamps null: false
t.references :user, index: true, foreign_key: true
end

型

class StandardAccount < ActiveRecord::Base
belongs_to :user
validates_presence_of :user_id  
validates_uniqueness_of :user_id
end

结构.sql(出于烦人的原因，我们使用结构.sql而不是模式(

ALTER TABLE ONLY public.standard_accounts
ADD CONSTRAINT fk_rails_6bc98ede2c FOREIGN KEY (user_id) REFERENCES public.users(id);

测试

RSpec.describe StripeStandardAccount, type: :model do
it { should belong_to(:user) }
it { should validate_presence_of(:user_id) }
it { should validate_uniqueness_of(:user_id) }
...

测试失败

1) StandardAccount should validate that :user_id is case-sensitively unique
Failure/Error: it { should validate_uniqueness_of(:user_id) }
ActiveRecord::InvalidForeignKey:
PG::ForeignKeyViolation: ERROR:  insert or update on table "standard_accounts" violates foreign key constraint "fk_rails_6bc98ede2c"
DETAIL:  Key (user_id)=(0) is not present in table "users".
: UPDATE "standard_accounts" SET "user_id" = $1, "updated_at" = $2 WHERE "standard_accounts"."id" = $3
# ./spec/models/standard_account_spec.rb:9:in `block (2 levels) in <top (required)>'
# ------------------
# --- Caused by: ---
# PG::ForeignKeyViolation:
#   ERROR:  insert or update on table "standard_accounts" violates foreign key constraint "fk_rails_6bc98ede2c"
#   DETAIL:  Key (user_id)=(0) is not present in table "users".

我想我可以编辑迁移并删除foreign_key: true位(这可能是在结构中创建外键约束的原因.sql(，但这是由 Rails 默认生成器添加的，虽然我不确定它的目的是什么，但这里似乎还有其他问题，因为这应该按原样工作。

Answer 1

解决此问题的方法是在运行应该测试之前创建StripeStandardAccount对象的实例。例如：

# Step 1
# If you are using FactoryBot (note: you need to use "!" with your "let")
let!(:stripe_standard_account) { create(:stripe_standard_account) }
# If you're not using FactoryBot
StripeStandardAccount.create(your-required-params-go-here)
# Step 2
# Then run your shoulda_matcher test
it { should validate_uniqueness_of(:user_id) }

这是因为您的测试用例需要一个现有实例来与它正在创建的实例进行比较。您不能询问对象的单个实例是否唯一。https://github.com/thoughtbot/shoulda-matchers/issues/682#issuecomment-78124438

Answer 2

事实证明，这实际上是由于应该匹配器库中的错误。我能够使用这种方法解决它。