验证与class_name的关联是否存在未通过测​​试

Question

我有这个型号：

class UserFriend < ActiveRecord::Base

  belongs_to :user
  validates :user, presence: true

  belongs_to :friend, class_name: User
  validates :friend, presence: true
end

这家工厂：

FactoryGirl.define do
  factory :user_friend do
    association :user
    association :friend, factory: :user
  end
end

和这个规范：

require 'spec_helper'

describe UserFriend do

  it "is invalid without a user" do
    expect(build(:user_friend, user: nil)).to have(1).errors_on(:user)
  end

  it "is invalid without a friend" do
    expect(build(:user_friend, friend: nil)).to have(1).errors_on(:friend)
  end
end

这是我收到的错误消息：

rspec spec/models/user_friend_spec.rb 
.F

Failures:

  1) UserFriend is invalid without a friend
     Failure/Error: expect(build(:user_friend, friend: nil)).to have(1).errors_on(:friend)
     NoMethodError:
       undefined method `attributes' for nil:NilClass
     # ./spec/models/user_friend_spec.rb:14:in `block (2 levels) in <top (required)>'

Finished in 0.65806 seconds
2 examples, 1 failure

Failed examples:

rspec ./spec/models/user_friend_spec.rb:13 # UserFriend is invalid without a friend

Randomized with seed 56390

测试正在通过第一个期望（用户）正确传递但是第二个（朋友）失败

Aclaration ：我没有使用HABTM关联，因为我在模型上有其他字段，我为该示例省略了。

Answer 1

在你的模型中，使用类名字符串而不是类常量，如下所示：

belongs_to :friend, class_name: 'User'