test_path_cookie.rb

ENV['RACK_ENV'] = 'test'
require 'sinatra'
require 'capybara/dsl'
require 'test/unit'

get '/path/set_cookie' do
  response.set_cookie('path_cookie', { value: 'test_cookie', path: '/path'} )
  "Cookie set"
end

get '/path/show_cookie' do
  "<span>#{request.cookies['path_cookie']}</span>"
end

get '/not_path/show_cookie' do
  "<span>#{request.cookies['path_cookie']}</span>"
end

Capybara.app = Sinatra::Application.new

class CookieTest < Test::Unit::TestCase
  include Capybara::DSL

  def test_cookies
    visit('/path/set_cookie')
    assert_text("Cookie set")
    visit('/path/show_cookie')
    assert_text('test_cookie')
    visit('/not_path/show_cookie')
    assert_no_text('test_cookie')
  end
end