spree i18n and globalize dance

ar_merge_party.rb

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

# 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 :products, force: true  do |t|
    t.string :name
  end

  create_table :translations, force: true  do |t|
    t.integer :product_id
    t.string :locale
  end

  create_table :variants, force: true  do |t|
    t.integer :product_id
  end
end

class Product < ActiveRecord::Base
  has_many :variants
  has_many :translations
end

class Translation < ActiveRecord::Base
  belongs_to :product
end

class Variant < ActiveRecord::Base
  belongs_to :product
end

class BugTest < Minitest::Test
  def test_merge_stuff
    product = Product.create! name: 'huhu'
    variant = Variant.create! product_id: product.id
    Translation.create! locale: 'en', product_id: product.id

    product_relation = Product.all
                              .preload(:translations)
                              .joins(:translations)
                              .merge(Translation.where(locale: 'en'))
                              .where(name: 'huhu')

    assert_equal variant, Variant.joins(:product).merge(product_relation).first
  end
end