Cucumber + Capybara – What we need for rails integration test
h2. What’s Capybara
Capybara is a webrat alternative which aims to support all browser simulators.
As you know, webrat can not run javascript on the webpage. In order to test javascript and AJAX based website we need install Selenium-clientgithub.com/ph7/selenium-client and learn extra API and also some configuratons.
Capybara give your a full stack solution.
You can use similar API drive webrat and selenium. And don’t need worry about configuraton.
What’s more, Capybara integrated Celerity which is a JRuby wrapper around HtmlUnit - a headless Java browser with JavaScript support. As your expect it using the same API.
And the killer feature of Capybara is you can easily change driver it use for testing. Not only in config file but also in runtime.
Why we need Cucumber
Before I introduce what is Cucumber, you need know what is BDD.
BDD is an evolution thinking behind TestDrivenDevelopment and AcceptanceTestDrivenPlanning
You don’t need worry about what the hell BDD is. After you start using Cucumber you will know. I promise.
Cucumber is allow you execute plain-text which written by BDD like format as automated tests.
There are plenty of materials on the internet which you can learn Cucumber
First place your need go is Ryan Bates’ RailsCasts Beginning with Cucumber
Then official Wiki of Cucumber will very helpful!!, and there also list some blog posts written by community
I won’t involve more about it. In my later blog post I will give you some tricks about using Cucumber.
Using Cucumber and Capybara
Install
Follow the instruction on Capybara:
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
And you also need install Cucumber
sudo gem install cucumber
Generate basic Cucumber folder structure and configuratons
Capybara is built to work nicely with Cucumber. You can easily generate Capybara style cucumber structure and configuraton.
script/generate cucumber --capybara
And maybe you also need install another gem named launchy which is helper class for launching cross-platform applications in a fire and forget manner.
sudo gem install launchy
Configuration
Available Configuration
Actually after you run the generator, you don’t need much more configuraton. Here I’ll list some of configuraton you can set.
You can specify it in features/support/env.rb file
Capybara.default_selector = :xpath #default selector , you can change to :css
Capybara.default_wait_time = 2 #When we testing AJAX, we can set a default wait time
Capybara.ignore_hidden_elements = false #Ignore hidden elements when testing, make helpful when you hide or show elements using javascript
Capybara.javascript_driver = :culerity #default driver when you using @javascript tag
Load rails test features
You can put codes below in features/support/env.rb file
Fixtures.reset_cache
fixtures_folder = File.join(RAILS_ROOT, 'test', 'fixtures')
fixtures = Dir[File.join(fixtures_folder, '*.yml')].map {|f| File.basename(f, '.yml') }
Fixtures.create_fixtures(fixtures_folder, fixtures)
end
And change
DatabaseCleaner.strategy = :truncation
OK. For now we already finish configuration. we can start writing cucumber test
How to run test under different testing driver
As you know cucumber support tags
Capybara using tag to specify different driver, it supports @javascript, @selenium, @celerity, @culerity and @rack_test tags
You can use it like:
Scenario: do something AJAXy
When I click the AJAX link
...
About how to write cucumber, you can check out Cucumber Wiki
About Capybara API
What I want to show you is how’s Capybara API look like.
This is all support Webrat like APIs in Capybara
:all, :attach_file, :body, :check, :choose, :click, :click_button, :click_link, :current_url, :drag, :evaluate_script,
:field_labeled, :fill_in, :find, :find_button, :find_by_id, :find_field, :find_link, :has_content?, :has_css?,
:has_no_content?, :has_no_css?, :has_no_xpath?, :has_xpath?, :locate, :save_and_open_page, :select, :source, :uncheck,
:visit, :wait_until, :within, :within_fieldset, :within_table, :has_link?, :has_no_link?, :has_button?, :has_no_button?,
:has_field?, :has_no_field?, :has_checked_field?, :has_unchecked_field?, :has_no_table?, :has_table?, :unselect,
:has_select?, :has_no_select?
]
Here are some examples which are not mentioned in Capybara Wiki.
page.has_css? "ul.error_messages li", :count => 5, :text => "error"
page.has_xpath? "//ul[@class='error_messages']/li", :count => 5, :text => "error"
#Equivalent
page.find(:css,"ul.error_messages li", :count => 5, :text => "error"
page.find(:xpath,"//ul[@class='error_messages']/li", :count => 5, :text => "error"
#Iterate all elements you found
all(:xpath,"//ul[@class='error_messages']/input").each do |node|
puts node.value
puts node.[:attribute_name]
puts node.click
puts node.set("aa") #set value
puts node.text
end
XPath
If you want to use XPath in Capybara, you need caution string escape.
Capybara give us a good example
if string.include?("'")
string = string.split("'", -1).map do |substr|
"'#{substr}'"
end.join(%q{,"'",})
"concat(#{string})"
else
"'#{string}'"
end
end
Summarize
Cucumber + Capybara will make your integration test easilier.
Finally we find a full stack integration test.
Have fun with it!
Thanks aslakhellesoy and jnicklas
PS:In this blog post I did memtion Celerity because I haven't tried it.
