Spec Out Your Cookies with Rspec

Here's something that got me this weekend and I couldn't find much info on it anywhere. So like my Internet taught me, I'm sharing. links_controller.rb
cookies[:phone] = params[:phone]
links_controller_spec.rb
it "should save the phone number in a cookie" do
  @my_cookies = mock('cookies')
  @my_cookies.stub!(:[]=)
  controller.stub!(:cookies).and_return(@my_cookies)

  @my_cookies.should_receive(:[]=).with(:phone, '804-755-7555')

  do_post
end
Here I'm making the expectation that a cookie will be set with the key of 'phone' and a value of a passed in parameter. My do_post method takes care of the post and passes in the parameter :phone => '804-755-7555'.