gistfile1.rb

class FoobarController < ActionController::Base
	def index
		session[:foo] = params[:foo]
		render :text => "saved session: #{session.inspect}"
	end
	
	def show
		render :text => "current session: #{session.inspect}"
	end
end

gistfile2.rb

require 'test_helper'

class FoobarTest < ActionController::IntegrationTest
  fixtures :all

  test "the truth" do
    get '/foobar', :foo => 'value'
    puts response.body
    get '/foobar/show'
    # expecting "current session: {:foo => 'value'}"
    # got "current session: {}"
    puts response.body
  end
end