Getting Up and Running with BDD on Rails
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This document provides an overview of behavior driven development (BDD) and Cucumber, a tool for BDD. It discusses BDD concepts like user stories, outside-in development, and the red-green-refactor cycle. It then covers installing and getting started with Cucumber in a Rails application, including writing features, step definitions, and using helpers like Webrat. It also discusses potential code smells with Cucumber and additional resources.
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Getting Up and Running with BDD on Rails
- 1. Behavior Driven Development with elegance and joy Getting Up and Running with BDD on Rails Nicholas Cancelliere email: [email protected] twitter: ozmox
- 2. Overview Behavior Driven Development Basic Concepts Cucumber from 10,000 ft Cucumber in the Rails Environment Writing your first Feature / Scenario Additional Resources
- 3. Behavior Driven “the next step” from Test-Driven Development tests what an object does rather than what it is intention more important than implementation outside-in approach offers all the benefits of TDD it is not Test-After Development
- 4. Benefits of TDD/BDD more productive (less debugging, fewer prod defects) helps drive programming design (KISS/YAGNI) delays implementation decisions greater level of code trust code more modularized, flexible and extensible
- 5. Outside-In User Client Value is in the views! Views Often html but can also be programmatic interfaces (such as XML or JSON), Controllers remember valuable to the user. Model
- 6. Red Green Refactor write enough test code to fail write just enough code to pass review your work and refactor
- 7. Red Green Refactor write enough test code to fail write just enough code to pass review your work and refactor
- 8. Red Green Refactor write enough test code to fail write just enough code to pass review your work and refactor
- 9. Red Green Refactor write enough test code to fail write just enough code to pass review your work and refactor
- 10. User Stories concept popular in Agile practices like Scrum and XP define the user’s role, what it is they need/want to do, and why they need/want (the value) As a us e r w i t h an a c o n t ac t s ddre s s b o so I c an e o k , I ne e d As a u s e r a s i l y re t r t o a dd w i t h an a ie ve t h e m e di t/de le t ddre s s b o l ate r. e c o n t ac t o k , I ne e d s so I c an d a te a n d ke e p i t up to m a n ag e a -to- As a us e r ble . w i t h an a my c on t a ddre s s b o c ts to o t h o k , I ne e d e r us e rs t to se nd o be sh a r e d.
- 11. Pop the Why Stack Ask “Why” up to 5 times Stop when you find the money Protect revenue Increase revenue Manage cost
- 12. Example Pop’in c: ‘People need to log in.’ d: ‘Why?’ c: ‘Um, identify users?’ d: ‘Why do you need to identify users?’ c: ‘So we know who’s publishing what.’ d: ‘Why would you need to know who publishes what?’ c: ‘If content belongs to someone it seems trustworthy.’ d: ‘Why does content need to be trustworthy?’ c: ‘People will be more interested in the content if so.’ d: ‘Why do you need people interested in the content?’ c: ‘So people come back and visit the site?’ d: ‘Why do you want people to come back and revisit?’ c: ‘More visits will increase our ad revenue.’
- 13. The Story As an author, I need to log into the site so that articles I create are associated to me and seem trustworthy, driving more traffic to the site.
- 14. The Story So that articles I create are associated to me, seem trustworthy and drive more traffic to the site, as an author, I need to log in.
- 15. Enter Cucumber Dan North ported JBehave to Ruby as RBehave RSpec merged RBehave in as the Story Runner First only supported Ruby for scenarios Later supported plain text, but still limited Aslak Hellesøy in 2008 rewrote Story Runner as Cucumber (named so by his fiancée) Cucumber has since taken to a life of it’s own
- 16. Cucumber written in Ruby itself and best matched with Ruby projects, but can be used for Java, .NET or Flex supports web apps in any language: integrates with Webrat, Watir, Selenium, et. al. Gherkin customization edit /cucumber/languages.yml minimum knowledge of Ruby required, you can pick it up and get going in a few days
- 17. Gherkin: the ‘unpickle’ variety a business readable, domain specific language that Cucumber understands two-stage parser for input file (plain text): 1. divides the file into sections (eg. feature, scenarios) 2. sections are divided into steps step-definitions are always matched by Ruby methods line-oriented (like YAML); line endings terminate statements (steps) and spaces or tabs to indent
- 18. Given When Then Used extensively in scenario definitions (Gherkin) Use “And” to chain together Given an invalid user When I go to the sign-in page And I fill in "userlogin" with "baduser" And I fill in "password" with "badpassword" And I submit "new_user_session" Then I should see "Sorry, we could not sign you in." And I should see "Login"
- 19. Installing in Rails gem install cucumber rspec-rails webrat /config/environments/test.rb config.gem 'rspec-rails', :lib => false config.gem 'rspec', :lib => false config.gem 'cucumber' config.gem 'webrat' rake gems:install RAILS_ENV=test script/generate cucumber script/generate rspec
- 20. Test::Unit Shoulda http://giantrobots.thoughtbot.com/2009/2/20/mixing- cucumber-with-test-unit /features/support/env.rb # require ‘cucumber/rails/rspec’ # require ‘webrat/rspec-rails’ /features/step_definitions/webrat_steps.rb # replace any matchers that use RSpec syntax Then /^I should see "(.*)"$/ do |text| # response.body.should =~ /#{text}/m assert_match /#{text}/m, @response.body end
- 21. Out of the Box Webrat comes with a bunch of handy helpers out of the box to make life easy for web application scenarios rake features - task to run all Cucumber tests /features review_past_events.feature /step_definitions event_steps.rb webrat_steps.rb /support env.rb paths.rb
- 22. Features
- 23. Features
- 24. Step Definition
- 25. Step Definition
- 26. Cukeing
- 27. Cukeing
- 28. Cukeing
- 29. Cukeing
- 30. Cukeing
- 31. Cukeing
- 32. Backgrounds
- 33. Backgrounds
- 34. Backgrounds
- 37. Remember... Cucumber defines the features you wish you had. RSpec (or Test::Unit) defines the interactions and objects you wish you had. You’re building a business domain language!
- 38. A Good Investment Conversation Acceptance Criteria Design Documentation Automated Functional and Integration Tests
- 39. What do I use? Speed Selenium + Webrat Unit Testing + Integration
- 40. Cucumber Smells Relying too much on state in your step-definitions Tests with no user value Too much concrete, less abstract
- 41. Cucumber Smells Relying too much on state in your step-definitions Tests with no user value Too much concrete, less abstract Given /^state$/ do @article = Article.create! end Given /^coupled by state/ do @article.title = ‘Bad’ end
- 42. Cucumber Smells Relying too much on state in your step-definitions Tests with no user value Too much concrete, less abstract Given /^check the db/ do Article.find(1).should_not == nil end
- 43. Cucumber Smells Relying too much on state in your step-definitions Tests with no user value Too much concrete, less abstract Given I go to the login page And I fill in “username” with “john” And I fill in “password” with “testpass” And I click “login”
- 44. Cucumber Smells Relying too much on state in your step-definitions Tests with no user value Too much concrete, less abstract Given I’m logged in
- 45. Cucumber Smells Relying too much on state in your step-definitions Tests with no user value Too much concrete, less abstract Given /I am logged in/ do @user = User.create!(:login => ‘john’, :password => ‘testpass’) And ‘I fill in “username” with “john”’ And ‘I fill in “password” with “testpass”’ And ‘I click “login”’ end
- 46. Additional Resources / Topics http://cukes.info The RSpec Book (beta @ PragProg.com) Textmate Bundles are available! Extending Cucumber with World Using Hooks (careful they’re global)