class Spec::Rails::Example::FunctionalExampleGroup

def cookies

cookies[:foo].should == 'bar'
get :index
cookies[:foo] = 'bar'

look like this:
is backwards-incompatible, so you have to change your examples to
values available with no access to other aspects of the cookie. This
tests (and therefore rspec controller specs), only making single
Rails 2.3 changes the way cookies are made available to functional

== Examples (Rails 2.3)

response.should be_redirect
get :index
cookies[:user_id] = {:value => '1234', :expires => 1.minute.ago}

== Examples (Rails 2.0 > 2.2)

them in controllers.
cookies in examples using the same API with which you set and read
responses cookies when reading one. This allows you to set and read
accesses the requests cookies when setting a cookie and the
ActionController::TestResponseBehaviour, returning a proxy that
Overrides the cookies() method in 
def cookies
  @cookies ||= Spec::Rails::Example::CookiesProxy.new(self)
end