capybara webkit or selenium or watir to simulate browser behavior

Sometimes we want to simulate browser behavior. The situation can be test or automation script.

##install capybara-webkit

#capybara-webkit need qt
sudo aptitude install libqt4-dev

##using capybara dsl

require 'capybara'
require 'capybara/dsl'

Capybara.default_driver = :webkit

module MyModule
  include Capybara::DSL

  def login!
    within("//form[@id='session']") do
      fill_in 'Login', :with => ''
      fill_in 'Password', :with => 'password'
      fill_in('First Name', :with => 'John')
      fill_in('Password', :with => 'Seekrit')
      fill_in('Description', :with => 'Really Long Text...')
      choose('A Radio Button')
      check('A Checkbox')
      uncheck('A Checkbox')
      attach_file('Image', '/path/to/image.jpg')
      select('Option', :from => 'Select Box')
      click_link 'Sign in'


It can be useful to take a snapshot of the page as it currently is and take a look at it:


You can also retrieve the current state of the DOM as a string using page.html.

print page.html

This is mostly useful for debugging. You should avoid testing against the contents of page.html and use the more expressive finder methods instead.

Finally, in drivers that support it, you can save a screenshot:


Calling remote servers

Normally Capybara expects to be testing an in-process Rack application, but you can also use it to talk to a web server running anywhere on the internets, by setting app_host:

Capybara.current_driver = :selenium
Capybara.app_host = ''

Note: the default driver (:rack_test) does not support running against a remote server. With drivers that support it, you can also visit any URL directly:


By default Capybara will try to boot a rack application automatically. You might want to switch off Capybara’s rack server if you are running against a remote application:

Capybara.run_server = false

Using the sessions manually

For ultimate control, you can instantiate and use a Session manually.

require 'capybara'

session =, my_rack_app)
session.within("//form[@id='session']") do
  session.fill_in 'Login', :with => ''
  session.fill_in 'Password', :with => 'password'
session.click_link 'Sign in'

XPath, CSS and selectors

Capybara does not try to guess what kind of selector you are going to give it, and will always use CSS by default. If you want to use XPath, you’ll need to do:

within(:xpath, '//ul/li') { ... }
find(:xpath, '//ul/li').text
find(:xpath, '//li[contains(.//a[@href = "#"]/text(), "foo")]').value

Alternatively you can set the default selector to XPath:

Capybara.default_selector = :xpath

Capybara allows you to add custom selectors, which can be very useful if you find yourself using the same kinds of selectors very often:

Capybara.add_selector(:id) do
  xpath { |id| XPath.descendant[XPath.attr(:id) == id.to_s] }

Capybara.add_selector(:row) do
  xpath { |num| ".//tbody/tr[#{num}]" }

Capybara.add_selector(:flash_type) do
  css { |type| "#flash.#{type}" }

The block given to xpath must always return an XPath expression as a String, or an XPath expression generated through the XPath gem. You can now use these selectors like this:

find(:id, 'post_123')
find(:row, 3)
find(:flash_type, :notice)

You can specify an optional match option which will automatically use the selector if it matches the argument:

Capybara.add_selector(:id) do
  xpath { |id| XPath.descendant[XPath.attr(:id) == id.to_s] }
  match { |value| value.is_a?(Symbol) }

Now use it like this:


This :id selector is already built into Capybara by default, so you don’t need to add it yourself.