使用Rspec测试after_hook

Question

我有标签系统和自动递增问题计数字段，它属于标签。 我正在使用Mongoid。

问题模型：

class Question

 has_and_belongs_to_many :tags, after_add: :increment_tag_count, after_remove: :decrement_tag_count
 after_destroy :dec_tags_count
 ...
 private
  def dec_tags_count
    tags.each do |tag|
      tag.dec_questions_count
    end
  end

和标签模型：

class Tag
  field :questions_count, type: Integer,default: 0
  has_and_belongs_to_many :questions

 def inc_questions_count
    inc(questions_count: 1)
  end

  def dec_questions_count
    inc(questions_count: -1)
  end

当我手动在浏览器中对其进行测试时，它可以正常工作；在添加或删除标签时，它会递增和递减tag.questions_count字段，但是我对问题模型after_destroy挂钩的测试总是会失败。

   it 'decrement tag count after destroy' do
      q = Question.create(title: 'Some question', body: "Some body", tag_list: 'sea')
      tag = Tag.where(name: 'Sea').first
      tag.questions_count.should == 1
      q.destroy
      tag.questions_count.should == 0
   end

expected: 0
     got: 1 (using ==)
     it {
    #I`ve tried
    expect{ q.destroy }.to change(tag, :questions_count).by(-1)
    }
   #questions_count should have been changed by -1, but was changed by 0 

需要帮忙...

Answer 1

这是因为您的tag仍引用原始Tag.where(name: 'Sea').first 。 我相信您可以在销毁以下问题后使用tag.reload （无法尝试确认），如下所示：

it 'decrement tag count after destroy' do
  ...
  q.destroy
  tag.reload
  tag.questions_count.should == 0
end

但是比这更好的是更新tag以指向q.tags.first ，我相信这是您想要的：

it 'decrement tag count after destroy' do
  q = Question.create(title: 'Some question', body: "Some body", tag_list: 'sea')
  tag = q.tags.first # This is going to be 'sea' tag.
  tag.questions_count.should == 1
  q.destroy
  tag.questions_count.should == 0
end