spec.rb

require 'rubygems'
require 'spec'
require 'spec/autorun'
require 'capybara'
require 'capybara/dsl'

Capybara.app = proc { |env| [200, {}, "Hello World"]}

Spec::Runner.configure do |config|
  config.include Capybara
end

describe "MyApp" do
  before do
    visit('/')
  end

  it "should show Hello World" do
    page.should have_content('Hello World')
  end

  it "should not show Hello Doug" do
    page.should_not have_content('Hello Doug')
  end
end