gem 'activerecord', '3.0.0'

require 'active_record'
require 'logger'
require 'pp'

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

ActiveRecord::Base.connection.create_table :widgets do |t|
  t.references :accessory
end

ActiveRecord::Base.connection.create_table :accessories do |t|
end

class Widget < ActiveRecord::Base
  belongs_to :accessory

  default_scope :include => :accessory
end

class Accessory < ActiveRecord::Base
end

a1 = Accessory.create

Widget.create(:accessory_id => a1.id)

pp Widget.columns.map(&:name)

puts Widget.exists?(:accessory_id => a1)  # should print "true"