Reproducing Rails callback bug

repro.rb

begin
  require 'bundler/inline'
rescue LoadError => e
  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
  raise e
end

gemfile(true) do
  source 'https://rubygems.org'
  gem 'rails', github: 'rails/rails'
  gem 'sqlite3'
end

require 'active_record'
require 'minitest/autorun'
require 'logger'

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :posts, force: true  do |t|
    t.string :name
  end

  create_table :comments, force: true  do |t|
    t.integer :post_id
  end
end

class Post < ActiveRecord::Base
  include Comparable
  after_destroy :log_delete
  has_many :comments
  
  def <=>(other)
    # return 0 unless other  # This will mask the problem.
    self.name <=> other.name
  end
  
  def log_delete
    puts "Logging #{self.class} #{attributes.inspect}"
    true
  end
end

class Comment < ActiveRecord::Base
  belongs_to :post
end

class BugTest < Minitest::Test
  def test_association_stuff
    post = Post.create!
    post.comments << Comment.create!

    assert_equal 1, post.comments.count
    assert_equal 1, Comment.count
    assert_equal post.id, Comment.first.post.id
    
    post.destroy   # This will crash, passing false to `other` in <=>
  end
end