Capybara¶ ↑

• github.com/jnicklas/capybara

Description:¶ ↑

Capybara aims to simplify the process of integration testing Rack applications, such as Rails, Sinatra or Merb. It is inspired by and aims to replace Webrat as a DSL for interacting with a web application. It is agnostic about the driver running your tests and currently comes bundled with rack-test, Culerity, Celerity and Selenium support built in. env.js support is available as the capybara-envjs gem.

Online documentation is availbable at rdoc.info.

Install:¶ ↑

Install as a gem:

sudo gem install capybara

On OSX you may have to install libffi, you can install it via MacPorts with:

sudo port install libffi

Development:¶ ↑

• Source hosted at GitHub.

• Please direct questions, discussions at the mailing list.

• Report issues on GitHub Issues

Pull requests are very welcome! Make sure your patches are well tested, Capybara is a testing tool after all. Please create a topic branch for every separate change you make.

Capybara uses bundler in development. To set up a development environment, simply do:

gem install bundler --pre
bundle install

Using Capybara with Cucumber¶ ↑

Capybara is built to work nicely with Cucumber. The API is very similar to Webrat, so if you know Webrat you should feel right at home. Support for Capybara is built into cucumber-rails 0.2. In your Rails app, just run:

script/generate cucumber --capybara

And everything should be set up and ready to go.

If you want to use Capybara with Cucumber outside Rails (for example with Merb or Sinatra), you’ll need to require Capybara and set the Rack app manually:

require 'capybara/cucumber'
Capybara.app = MyRackApp

Now you can use it in your steps:

When /I sign in/ do
  within("#session") do
    fill_in 'Login', :with => 'user@example.com'
    fill_in 'Password', :with => 'password'
  end
  click_link 'Sign in'
end

Default and current driver¶ ↑

You can set up a default driver for your features. For example if you’d prefer to run Selenium, you could do:

require 'capybara/rails'
require 'capybara/cucumber'
Capybara.default_driver = :selenium

You can change the driver temporarily:

Capybara.current_driver = :culerity
Capybara.use_default_driver

You can do this in Before and After blocks to temporarily switch to a different driver. Note that switching driver creates a new session, so you may not be able to switch in the middle of a Scenario.

Cucumber and Tags¶ ↑

Capybara sets up some tags for you to use in Cucumber. Often you’ll want to run only some scenarios with a driver that supports JavaScript, Capybara makes this easy: simply tag the scenario (or feature) with @javascript:

@javascript
Scenario: do something AJAXy
  When I click the AJAX link
  ...

You can change which driver Capybara uses for JavaScript:

Capybara.javascript_driver = :culerity

There are also explicit @selenium, @culerity and @rack_test tags set up for you.

Selenium¶ ↑

At the moment, Capybara supports Webdriver, also called Selenium 2.0, not Selenium RC. Provided Firefox is installed, everything is set up for you, and you should be able to start using Selenium right away.

Celerity¶ ↑

Celerity only runs on JRuby, so you’ll need to install the celerity gem under JRuby:

jruby -S gem install celerity

Culerity¶ ↑

Install celerity as noted above, make sure JRuby is in your path. Note that Culerity doesn’t seem to be working under Ruby 1.9 at the moment.

env.js¶ ↑

The capybara-envjs driver uses the envjs gem (GitHub, rubygems.org) to interpret JavaScript outside the browser. The driver is installed by installing the capybara-envjs gem:

gem install capybara-envjs

More info about the driver and env.js are available through the links above. The envjs gem only supports Ruby 1.8.7 at this time.

The DSL¶ ↑

Capybara’s DSL is inspired by Webrat. While backwards compatibility is retained in a lot of cases, there are certain important differences.

Unlike in Webrat, all searches in Capybara are *case sensitive*. This is because Capybara heavily uses XPath, which doesn’t support case insensitivity.

Navigating¶ ↑

You can use the visit method to navigate to other pages:

visit('/projects')
visit(post_comments_path(post))

The visit method only takes a single parameter, the request method is always GET.

You can get the current path of the browsing session for test assertions:

current_path.should == post_comments_path(post)

Clicking links and buttons¶ ↑

You can interact with the webapp by following links and buttons. Capybara automatically follows any redirects, and submits forms associated with buttons.

click_link('id-of-link')
click_link('Link Text')
click_button('Save')
click_link_or_button('Link Text')
click_link_or_button('Button Value')

Interacting with forms¶ ↑

Forms are everywhere in webapps, there are a number of tools for interacting with the various form elements:

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')

Querying¶ ↑

Capybara has a rich set of options for querying the page for the existence of certain elements, and working with and manipulating those elements.

page.has_xpath?('//table/tr')
page.has_css?('table tr.foo')
page.has_content?('foo')

You can these use with RSpec’s magic matchers:

page.should have_xpath('//table/tr')
page.should have_css('table tr.foo')
page.should have_content('foo')
page.should have_no_content('foo')

Note that page.should have_no_xpath is preferred over page.should_not have_xpath. Read the section on asynchronous JavaScript for an explanation.

Finding¶ ↑

You can also find specific elements, in order to manipulate them:

find_field('First Name').value
find_link('Hello').visible?
find_button('Send').click

find(:xpath, "//table/tr").click
find("#overlay").find("h1").click
all('a').each { |a| a[:href] }

Note that find will wait for an element to appear on the page, as explained in the AJAX section. If the element does not appear it will raise an error.

These elements all have all the Capybara DSL methods available, so you can restrict them to specific parts of the page:

find('#navigation').click_link('Home')
find('#navigation').should have_button('Sign out')

Scoping¶ ↑

Capybara makes it possible to restrict certain actions, such as interacting with forms or clicking links and buttons, to within a specific area of the page. For this purpose you can use the generic within method. Optionally you can specify which kind of selector (CSS or XPath to use).

within("//li[@id='employee']") do
  fill_in 'Name', :with => 'Jimmy'
end

within(:css, "li#employee") do
  fill_in 'Name', :with => 'Jimmy'
end

You can choose which kind of selector Capybara uses by default, by setting Capybara.default_selector.

There are special methods for restricting the scope to a specific fieldset, identified by either an id or the text of the fieldet’s legend tag, and to a specific table, identified by either id or text of the table’s caption tag.

within_fieldset('Employee') do
  fill_in 'Name', :with => 'Jimmy'
end

within_table('Employee') do
  fill_in 'Name', :with => 'Jimmy'
end

Scripting¶ ↑

In drivers which support it, you can easily execute JavaScript:

page.execute_script("$('body').empty()")

For simple expressions, you can return the result of the script. Note that this may break with more complicated expressions:

result = page.evaluate_script('4 + 4');

Debugging¶ ↑

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

save_and_open_page

Asynchronous JavaScript (AJAX and friends)¶ ↑

When working with asynchronous JavaScript, you might come across situations where you are attempting to interact with an element which is not yet present on the page. Capybara automatically deals with this by waiting for elements to appear on the page.

When issuing instructions to the DSL such as:

click_link('foo')
click_link('bar')
page.should have_content('baz')

If clicking on the foo link causes triggers an asynchronous process, such as an AJAX request, which, when complete will add the bar link to the page, clicking on the bar link would be expeced to fail, since that link doesn’t exist yet. However Capybara is smart enought to retry finding the link for a brief period of time before giving up and throwing an error. The same is true of the next line, which looks for the content baz on the page; it will retry looking for that content for a brief time. You can adjust how long this period is (the default is 2 seconds):

Capybara.default_wait_time = 5

Be aware that because of this behaviour, the following two statements are not equivalent, and you should always use the latter!

page.should_not have_xpath('//a')
page.should have_no_xpath('//a')

The former would incorrectly wait for the content to appear, since the asynchronous process has not yet removed the element from the page, it would therefore fail, even though the code might be working correctly. The latter correctly waits for the element to disappear from the page.

Using the DSL outside cucumber¶ ↑

You can mix the DSL into any context, for example you could use it in RSpec examples. Just load the DSL and include it anywhere:

require 'capybara'
require 'capybara/dsl'

Capybara.default_driver = :culerity

module MyModule
  include Capybara

  def login!
    within("//form[@id='session']") do
      fill_in 'Login', :with => 'user@example.com'
      fill_in 'Password', :with => 'password'
    end
    click_link 'Sign in'
  end
end

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 = 'http://www.google.com'
...
visit('/')

Note that rack-test does not support running against a remote server. With drivers that support it, you can also visit any URL directly:

visit('http://www.google.com')

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 = Capybara::Session.new(:culerity, my_rack_app)
session.within("//form[@id='session']") do
  session.fill_in 'Login', :with => 'user@example.com'
  session.fill_in 'Password', :with => 'password'
end
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, if you want to use XPath with your ‘within’ declarations for example, 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
find('//ul/li').text

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::Selector.add(:id) { |id| XPath.descendant[XPath.attr(:id) == id.to_s] }
Capybara::Selector.add(:row) { |num| ".//tbody/tr[#{num}]" }

These 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)

You can specify an optional :for option which will automatically use the selector if it matches the argument to find using ===:

Capybara::Selector.add(:id, :for => Symbol) { |id| XPath.descendant[XPath.attr(:id) == id.to_s] }

Now use it like this:

find(:post_123)

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

Beware the XPath // trap¶ ↑

In XPath the expression // means something very specific, and it might not be what you think. Contrary to common belief, // means “anywhere in the document” not “anywhere in the current context”. As an example:

page.find(:xpath, '//body').all(:xpath, '//script')

You might expect this to find all script tags in the body, but actually, it finds all script tags in the entire document, not only those in the body! What you’re looking for is the .// expression which means “any descendant of the current node”:

page.find(:xpath, '//body').all(:xpath, './/script')

The same thing goes for within:

within(:xpath, '//body') do
  page.find(:xpath, './/script')
  within(:xpath, './/table/tbody') do
    ...
  end
end

Configuring and adding drivers¶ ↑

Capybara makes it convenient to switch between different drivers. It also exposes an API to tweak those drivers with whatever settings you want, or to add your own drivers. This is how to switch the selenium driver to use chrome:

Capybara.register_driver :selenium do |app|
  Capybara::Driver::Selenium.new(app, :browser => :chrome)
end

However, it’s also possible to give this a different name, so tests can switch between using different browsers effortlessly:

Capybara.register_driver :selenium_chrome do |app|
  Capybara::Driver::Selenium.new(app, :browser => :chrome)
end

Whatever is returned from the block should conform to the API described by Capybara::Driver::Base, it does not however have to inherit from this class. Gems can use this API to add their own drivers to Capybara.

Gotchas:¶ ↑

• Access to session and request is not possible from the test, Access to response is limited. Some drivers allow access to response headers and HTTP status code, but this kind of functionality is not provided by some drivers, such as Selenium.

• Access to Rails specific stuff (such as controller) is unavailable, since we’re not using Rails’ integration testing.

• Freezing time: It’s common practice to mock out the Time so that features that depend on the current Date work as expected. This can be problematic, since Capybara’s AJAX timing uses the system time, resulting in Capybara never timing out and just hanging when a failure occurs. It’s still possible to use plugins which allow you to travel in time, rather than freeze time. One such plugin is Timecop.

License:¶ ↑

(The MIT License)

Copyright © 2009 Jonas Nicklas

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.