rails order join or bug

incorrect_join_order.rb

# frozen_string_literal: true

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"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  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|
  end

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

  create_table :attachements, force: true do |t|
  end
end

class Post < ActiveRecord::Base
  has_many :comments
  scope :double_left_joins, -> {
    left_joins(:comments)
      .joins("LEFT JOIN attachements ON attachements.id = comments.attachement_id")
  }
end

class Comment < ActiveRecord::Base
  belongs_to :post
end

class Attachement < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_association_stuff
    attachement = Attachement.create!
    post = Post.create!
    post.comments << Comment.create!(attachement_id: attachement.id)

    assert_equal 1, post.comments.count
    assert_equal 1, Comment.count
    assert_equal post.id, Comment.first.post.id
    assert_equal 1, Post.double_left_joins.count
  end
end