Confirm Rails 4 behavior for includes inside has_many scope

has_many_through_with_includes_inside_scope_rails4.rb

unless File.exists?('Gemfile')
  File.write('Gemfile', <<-GEMFILE)
    source 'https://rubygems.org'
    gem 'rails', '4.2.10'
    gem 'sqlite3'
  GEMFILE

  system 'bundle'
end

require 'bundler'
Bundler.setup(:default)

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 :concepts do |t|
    t.string :name, default: 'Concept test'
  end

  create_table :links do |t|
    t.references :concept
    t.references :entry
    t.datetime :starts_at
  end
  
  create_table :entries do |t|
    t.string :name, default: '1st entry'
  end

  create_table :scores do |t|
    t.integer :score, default: 0
    t.references :entry
  end
end

class Score < ActiveRecord::Base
  belongs_to :concept
end

class Concept < ActiveRecord::Base
  has_many :links
  has_many :entries, through: :links
  has_many :top_entries,->{ includes(:score).order('scores.score DESC').references(:score).limit(3) }, through: :links, source: :entry
end

class Link < ActiveRecord::Base
  belongs_to :concept
  belongs_to :entry
end

class Entry < ActiveRecord::Base
  has_one :score
  has_many :links
end

class BugTest < Minitest::Test
  def test_association_stuff
    concept = Concept.create!
    concept2 = Concept.create!(name: '2nd concept test')
    
    entry = Entry.create!
    entry2 = Entry.create!(name: '2nd entry test')
    entry3 = Entry.create!(name: '3rd entry test')
    entry4 = Entry.create!(name: '4th entry test')
    entry5 = Entry.create!(name: '5th entry test')
    entry6 = Entry.create!(name: '6th entry test')
    entry7 = Entry.create!(name: '7th entry test')
    
    concept.links << Link.create!(starts_at: DateTime.current, entry_id: entry.id)
    concept.links << Link.create!(starts_at: DateTime.current, entry_id: entry6.id)
    concept.links << Link.create!(starts_at: DateTime.current, entry_id: entry7.id)
    
    concept2.links << Link.create!(starts_at: DateTime.current, entry_id: entry2.id)
    concept2.links << Link.create!(starts_at: DateTime.current, entry_id: entry3.id)
    concept2.links << Link.create!(starts_at: DateTime.current, entry_id: entry4.id)
    concept2.links << Link.create!(starts_at: DateTime.current, entry_id: entry5.id)
    
    entry.score = Score.create!(score: 0)
    entry2.score = Score.create!(score: 1)
    entry3.score = Score.create!(score: 2)
    entry4.score = Score.create!(score: 3)
    entry5.score = Score.create!(score: 4)
    entry6.score = Score.create!(score: 5)
    entry7.score = Score.create!(score: 6)

    concepts =  Concept.includes(:top_entries)
    concepts.each_with_index do |c,i|
      puts "----- Concept number #{i} ------------"
      puts c.top_entries.map(&:name)
    end
  end
end