ruby-on-rails – 为什么我在Rails模型回调中得到这个“未定义的

Testing started at 1:55 … rake aborted!
undefined method ‘markdown_changed_or_html_nil?’ for #<Post:0x000000053603d0>
C:/Users/user/Documents/GitHub/jw/app/models/post.rb:7:in <class:Post>
C:/Users/user/Documents/GitHub/jw/app/models/post.rb:1:in <top (required)>
C:/Users/user/Documents/GitHub/jw/test/test_helper.rb:12:in <class:TestCase>
C:/Users/user/Documents/GitHub/jw/test/test_helper.rb:5:in <top (required)>
C:/Users/user/Documents/GitHub/jw/test/models/post_test.rb:1:in <top (required)>
-e:1:in ‘load’
-e:1:in ” Tasks: TOP => test:run => test:units (See full trace by running task with –trace) Run options: –seed 13458

# Running tests:

Finished tests in 0.002000s,0.0000 tests/s,0.0000 assertions/s.

0 tests,0 assertions,0 failures,0 errors,0 skips

Process finished with exit code 1

这是有问题的模型：

class Post < ActiveRecord::Base
  include ActiveModel::Dirty

  before_save :convert_markdown,if: :markdown_changed_or_html_nil?

  belongs_to :user
  validates :user,:title,:content_markdown,{ presence: true,on: create }
  validates_associated :user

  protected
    def convert_markdown
      markdown = Redcarpet::Markdown.new(Redcarpet::Render::HTML,space_after_headers: true,underline: true)
      self.content_html = markdown.render(content_markdown)
    end

    def markdown_changed_or_html_nil?
      content_markdown.changed? || content_markdown.nil?
    end
end

我正在使用Ruby 2.0.0和Rails 4.0.2.

我可能已经犯了一个非常基本的错误 – 我还在学习Rails.

编辑：这是post_test.rb

require 'test_helper'

class PostTest < ActiveSupport::TestCase
  test 'saving an empty object fails' do
    new_post = Post.new

    assert_not new_post.save
  end

  test 'validates that given user id corresponds to user' do
    # This will create a user with a given id so we can use the next one up
    test_user = User.create({ name: 'Johnny Test',email: 'johnny.test@example.com',password: 'password',password_confirmation: 'password' })

    # Use next id up - there's no reason it should be taken at this point
    given_user_id = test_user.id + 1

    post_with_invalid_user = Post.new({ title: 'Look at my glorious title',content_markdown: 'Sick content',user_id: given_user_id })

    assert_not post_with_invalid_user.save
  end

  test 'converts markdown into html' do
    # This is a really really basic test just to make sure a conversion happens
    new_post = Post.new({ title: 'Check out this markdown,baby',content_markdown: 'I got some *sick* markdown',user_id: users(:paul).id })

    assert_equal '<p>I got some <em>sick</em> markdown</p>',new_post.content_html
  end
end