example using capybara and capybara-webkit

ratings_spec.rb

require 'spec_helper'

feature "Rating" do
  let(:current_user){ Factory(:user) }
  let(:post){ Factory(:post) }
  let!(:comment){ Factory(:comment, :commentable => post) }

  background do
    sign_in_as(current_user)
  end

  scenario 'rating a comment', :js => true do
    visit post_path(post)

    within('.rating') do
      page.should have_link "thumbs_up"
      page.should have_content "0"
    end

    click_link 'thumbs_up'
    wait_until{ page.has_no_selector?(:spinning) }

    within('.rating') do
      page.should_not have_link "thumbs_up"
      page.should have_content "1"
    end
  end
end