gistfile1.rb

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

  system 'bundle'
end

require 'bundler'
Bundler.setup(:default)

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

# Ensure backward compatibility with Minitest 4
Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)

ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
ActiveRecord::Base.logger = Logger.new(STDOUT)

# Schema
ActiveRecord::Schema.define do
  ActiveRecord::Base.connection.create_table(:blogs)

  ActiveRecord::Base.connection.create_table(:posts) do |t|
    t.integer :blog_id
  end
end

# Models
class Blog < ActiveRecord::Base
  has_many :posts
  has_many :limited_posts, -> { order(:id).limit(2) }, class_name: 'Post'
  has_many :grouped_posts, -> { group(:blog_id) }, class_name: 'Post'
  has_many :offset_posts, -> { offset(2) }, class_name: 'Post'
end

class Post < ActiveRecord::Base
  belongs_to :blog
end

class BugTest < Minitest::Test
  def setup
    Blog.delete_all
    Post.delete_all
  end

  def test_eager_load_association_with_limit
    blog = Blog.create!
    3.times { blog.posts.create! }
    blog = Blog.includes(:limited_posts).first!
    assert_equal(2, blog.limited_posts.size)
    assert_equal(Post.order(:id).limit(2), blog.limited_posts)
  end

  def test_eager_load_association_with_group
    blog = Blog.create!
    3.times { blog.posts.create! }
    blog = Blog.includes(:grouped_posts).first!
    assert_equal(1, blog.grouped_posts.size)
  end

  def test_eager_load_association_with_offset
    blog = Blog.create!
    3.times { blog.posts.create! }
    blog = Blog.includes(:offset_posts).first!
    assert_equal(1, blog.offset_posts.size)
  end
end