copy_ivars.rb

module SetupOnce
  def self.included(base)
    base.class_eval do
      attr_accessor :copy_ivars_blocks, :copy_ivars_binding, :copy_ivar_names
      alias_method_chain :run_current_setup_blocks, :copy_ivars
      alias_method_chain :initialize, :copy_ivars
      alias_method_chain :build, :copy_ivars
    end
  end

  def initialize_with_copy_ivars(name, parent, &blk)
    Shoulda.add_context(self)
    self.copy_ivars_blocks = []
    self.copy_ivar_names = []
    self.copy_ivars_binding = nil
    Shoulda.remove_context

    initialize_without_copy_ivars(name, parent, &blk)
  end

  def copy_ivars(&blk)
    self.copy_ivars_blocks << blk
  end

  def build_with_copy_ivars
    self.shoulds.unshift({:name => 'start transaction', :before => nil, :block => proc { @shoulda_context.start_db_transaction } })
    self.shoulds.push({:name => 'stop transaction', :before => nil, :block => proc { @shoulda_context.stop_db_transaction } })

    build_without_copy_ivars
  end

  def run_current_setup_blocks_with_copy_ivars(binding)
    if self.copy_ivar_names.blank?
      self.copy_ivars_binding = binding.clone
      self.copy_ivars_blocks.map {|ci| ci.bind(self.copy_ivars_binding).call}

      self.copy_ivar_names = self.copy_ivars_binding.instance_variables
    end

    self.copy_ivar_names.each do |ivar|
      original = self.copy_ivars_binding.instance_variable_get(ivar)
      binding.instance_variable_set(ivar, original)
    end

    run_current_setup_blocks_without_copy_ivars(binding)
  end

  def start_db_transaction
    ::ActiveRecord::Base.connection.increment_open_transactions
    ::ActiveRecord::Base.connection.transaction_joinable = false
    ::ActiveRecord::Base.connection.begin_db_transaction
  end

  def stop_db_transaction
    if ::ActiveRecord::Base.connection.open_transactions != 0
      ::ActiveRecord::Base.connection.rollback_db_transaction
      ::ActiveRecord::Base.connection.decrement_open_transactions
    end
  end
end

Shoulda::Context.send :include, SetupOnce