# File lib/railsbench/railsbenchmark.rb, line 185
  def update_test_session_data(session_data)
    if @rack_middleware
      session_options = ActionController::Base.session_options
      merge_url_specific_session_data = lambda do |env|
        old_session_data = env["rack.session"]
        # $stderr.puts "data in old session: #{old_session_data.inspect}"
        new_session_data = old_session_data.merge(session_data || {})
        # $stderr.puts "data in new session: #{new_session_data.inspect}"
        env["rack.session"] = new_session_data
        [200, {}, ""]
      end
      @session_store.instance_eval { @app = merge_url_specific_session_data }
      env = {}
      env["HTTP_COOKIE"] = cookie
      # debugger
      @session_store.call(env)
    else
      dbman = ActionController::CgiRequest::DEFAULT_SESSION_OPTIONS[:database_manager]
      old_session_data = dbman.new(@session).restore
      # $stderr.puts old_session_data.inspect
      new_session_data = old_session_data.merge(session_data || {})
      new_session_data.each{ |k,v| @session[k] = v }
      @session.update
    end
  end