Cucumber is a tool that executes plain-text behavioral tests written in Gherkin and maps them to code via step definitions to automate testing; Gherkin is a business-readable language used to describe software behavior without detailing implementation; Cucumber uses Ruby and drivers like Capybara to simulate user interactions and check outcomes of the automated tests.

2. What is Cucumber?
Cucumber is a tool that executes plain-text functional descriptions as
automated tests.
Here is an example:
BDD: Behavior Driven Development

3. Running test cases

4. How Cucumber works: Gherkin
• Gherkin is the language that Cucumber
understands.
• It is a Business Readable, Domain Specific
Language that lets you describe software’s
behaviour without detailing how that behaviour
is implemented.
• So everyone can write Gherkin.
• Gherkin serves two purposes – documentation
and automated tests. The third is a bonus feature
– when it yells in red it’s talking to you, telling
you what code you should write.

5. Gherkin Example
1: Feature: Some terse yet descriptive text of what is desired
2: In order to realize a named business value
3: As an explicit system actor
4: I want to gain some beneficial outcome which furthers the goal
5:
6: Scenario: Some determinable business situation
7: Given some precondition
8: And some other precondition
9: When some action by the actor
10: And some other action
11: And yet another action
12: Then some testable outcome is achieved
13: And something else we can check happens too
14:
15: Scenario: A different situation
16: ...

6. Gherkin Documents

7. How Cucumber works: Backgrounder
• Language: Ruby, etc.
Gherkin:
Scenario: Users can enter an invoice item
. . .
Then I enter a product quantity of 5
Step definition:
When /enter a product quantity of (d+)/ do |quantity|
pending "TODO: Do we need to have a product code passed as well?"
End

8. How Cucumber works: Capybara
• Capybara helps you test Rails and Rack
applications by simulating how a real user
would interact with your app.
• It is agnostic about the driver running your
tests and comes with Rack::Test and Selenium
support built in.

9. Capybara Example
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

10. Capybara DSL
• Navigation: visit
• Interact: attach_file, text, check, choose, click_link_or_button,
click_button, click_link, field_labeled, fill_in, select, unselect, uncheck,
click_on
• Find: all, first, find, find_button, find_by_id, find_field, find_link
• Query: has_content?, has_css?, has_no_content?, has_no_css?,
has_no_xpath?, has_xpath?, 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?, has_select?,
has_no_select?, has_selector?, has_no_selector?,
has_no_checked_field?, has_no_unchecked_field?
• Debugging: save_page, save_and_open_page

11. Capybara Drivers
• RackTest
– Default driver
– Doesn’t support Javascript
• Webkit
– Uses QtWebKit to start a rendering engine
process.
– Execute Javascript
• Selenium
– Start a Firefox to test

12. Cucumber Architecture
Cucumber
Gherkin Backgrounder
Given When Then Ruby code Capybara
DSL Drivers
Navigating Interaction Querying Finding Scoping Debugging RackTest Webkit Selenium
Firefox …

13. Install cucumber in Rails 2.3
gem "capybara", "1.1.1"
gem "cucumber", "1.1.0"
gem "cucumber-rails", "0.3.2”
$ script/generate cucumber --capybara
create config/cucumber.yml #cucumber command params
create config/environments/cucumber.rb #cucumber rails env
create script/cucumber
create features/step_definitions #step definitions
create features/step_definitions/web_steps.rb #generalstep definitions
create features/support #cucumber configure files
create features/support/paths.rb #cucumber path configure
create features/support/env.rb #cucumber env configure
create lib/tasks #cucumber rake tasks
create lib/tasks/cucumber.rake

14. Write your first cucumber test case
It’s really, really recommended that you write your features by hand – in collaboration
with your customer / business analyst / domain expert / interaction designer.
However, to get you started you can use the feature generator to generate the first
few features:
$ script/generate feature Frooble name:string color:string description:text
exists features/step_definitions
create features/manage_froobles.feature #gherkin, user stories
create features/step_definitions/frooble_steps.rb #ruby, step definitions

15. How to use Cucumber?
1. Describe behaviour in plain text
2. Write a step definition in Ruby
3. Run and watch it fail
4. Write code to make the step pass
5. Run again and see the step pass
6. Repeat 2-5 until green like a cuke
7. Repeat 1-6 until the money runs out

16. More info?