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

BDD: Behavior Driven Development

Running test cases

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.

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 actor10: And some other action11: And yet another action12: Then some testable outcome is achieved13: And something else we can check happens too14: 15: Scenario: A different situation16: ...

Gherkin Documents

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

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.

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

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

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

Cucumber Architecture

Cucumber

Gherkin

Given When Then

Backgrounder

Ruby code Capybara

DSL

Navigating Interaction Querying Finding Scoping Debugging

Drivers

RackTest Webkit Selenium

Firefox …

Install cucumber in Rails 2.3gem "capybara", "1.1.1"gem "cucumber", "1.1.0"gem "cucumber-rails", "0.3.2”

$ script/generate cucumber --capybaracreate config/cucumber.yml #cucumber command paramscreate config/environments/cucumber.rb #cucumber rails envcreate script/cucumbercreate features/step_definitions #step definitionscreate features/step_definitions/web_steps.rb #generalstep definitionscreate features/support #cucumber configure filescreate features/support/paths.rb #cucumber path configurecreate features/support/env.rb #cucumber env configurecreate lib/tasks #cucumber rake taskscreate lib/tasks/cucumber.rake

Write your first cucumber test caseIt’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

How to use Cucumber?

1. Describe behaviour in plain text2. Write a step definition in Ruby3. Run and watch it fail4. Write code to make the step pass5. Run again and see the step pass6. Repeat 2-5 until green like a cuke7. Repeat 1-6 until the money runs out

More info?