rails_12725.rb

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

  system 'bundle'
end

require 'bundler'
Bundler.setup(:default)

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

puts "Using ActiveRecord #{ActiveRecord::VERSION::STRING}"

# 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) do |t|
  end

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

  ActiveRecord::Base.connection.create_table(:authors) do |t|
  end

  ActiveRecord::Base.connection.create_table(:addresses) do |t|
    t.string :city
    t.integer :author_id
  end
end

# Models
class Blog < ActiveRecord::Base
  has_many :posts
  has_many :authors, -> { includes(:address).where('addresses.city IS NOT NULL').references(:address) }, through: :posts
end

class Post < ActiveRecord::Base
  belongs_to :blog
  belongs_to :author
end

class Author < ActiveRecord::Base
  has_many :posts
  has_one :address
end

class Address < ActiveRecord::Base
  belongs_to :author
end

class BugTest < Minitest::Test

  def test_bug
    blog = Blog.create!
    author = Author.create!
    Address.create!(author: author, city: 'Boston')
    blog.posts.create(author: author)

    # Without eager loading
    assert_equal([author], Blog.first.authors)

    # With eager loading
    assert_equal([author], Blog.includes(:authors).first.authors)
  end

end