RubyConf Colombia 2017: Building the New Rails System Test Framework

At the 2014 RailsConf DHH declared system testing would be added to Rails. Three years later, Rails 5.1 makes good on that promise by introducing a new testing framework: ActionDispatch::SystemTestCase. The feature brings system testing to Rails with zero application configuration by adding Capybara integration. After a demonstration of the new framework, we'll walk through what's uniquely involved with building OSS features & how the architecture follows the Rails Doctrine. We'll take a rare look at what it takes to build a major feature for Rails, including goals, design decisions, & roadblocks.

Transcript

1. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run BUILDING THE NEW RAILS System Tests
2. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run ¡Hola! Soy Eileen M. Uchitelle
3. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run I’m a Systems Engineer @
4. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run I’m on the Core Team
5. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run You can find me online @eileencodes
6. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run BUILDING THE NEW RAILS System Tests
7. At the 2014 RailsConf…
9. IS DEAD
10. Today we do [Rails does] nothing to encourage full system tests. There's no default answer in the stack. That's a mistake we’re going to fix. “ —DHH in “TDD is dead. Long live testing.” http://david.heinemeierhansson.com/2014/tdd-is-dead-long-live-testing.html
11. 3 years later…
12. Zomg, Rails 5.1 has system testing!!1!11!
13. Wait, what’s a system test?
14. Tests your application as a system
15. gem 'capybara', '> 2.13.0' gem 'selenium-webdriver' Rails 5.1 Gemfile
16. application_system_test_case.rb require 'test_helper' class ApplicationSystemTestCase < ActionDispatch::SystemTestCase driven_by :selenium, using: :chrome, screen_size: [1400, 1400] end
17. require "application_system_test_case" class PostsTest < ApplicationSystemTestCase test "visiting the index" do visit posts_url assert_selector "h1", text: "Post" end end
18. rails test:system Running System Tests
20. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run SYSTEM TESTING Why did it take 3 years?
21. Integration tests were slowww….
24. Yo, can you make my system test promise come true?
25. I had never used Capybara before
26. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run SYSTEM TESTING Guiding Principles
27. 1. Optimize for programmer happiness 2. Convention over configuration 3. The menu is omakase 4. No one paradigm 5. Exalt beautiful code 6. Provide sharp knives 7. Value integrated systems 8. Progress over stability 9. Push up a big tent The Rails Doctrine
28. Optimize for programmer happiness
29. require 'test_helper' # set the driver Capybara.current_driver = :selenium # register the driver & browser Capybara.register_driver :selenium do |app| Capybara::Selenium::Driver.new(app, browser: :chrome).tap do |driver| driver.browser.manage.window.size = Selenium::WebDriver::Dimension.new(*[1400, 1400]) end end # set the server Capybara.server = :puma Capybara.always_include_port = true # register the server Capybara.register_server :puma do |app, port, host| Rack::Handler::Puma.run(app, Port: port, Threads: "0:1") end
30. There is zero configuration required to use Capybara with Rails 5.1
31. require 'test_helper' class ApplicationSystemTestCase < ActionDispatch::SystemTestCase driven_by :selenium, using: :chrome, screen_size: [1400, 1400] end
32. Value integrated systems
33. Rails as a whole now addresses system testing
34. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run SYSTEM TESTING Implementation & Architecture
35. Config defaults: Why Selenium?
36. Can see the tests running in the browser
37. Better for beginners learning Rails and Capybara
38. driven_by :selenium Driver Options
39. driven_by :poltergeist Driver Options
40. Config defaults: Why Chrome?
41. Chrome is widely used
42. For awhile, Firefox was broken with Selenium
43. driven_by :selenium, using: :chrome Driver Options
44. driven_by :selenium, using: :firefox Driver Options
45. Driver Options driven_by :selenium, using: :firefox
 screen_size: [1400, 1400]
46. Driver Options driven_by :selenium, using: :firefox
 options: { url: "http://chrome:4444/hub" }
47. Config defaults: Failure Screenshots
48. def after_teardown take_failed_screenshot Capybara.reset_sessions! super end Driver Options
50. Database Cleaner not required
51. Test transaction opens a connection
52. Puma opens a second connection Test transaction opens a connection
53. The first connection can’t see the data inserted on the second connection
55. I asked for help from @tenderlove & @matthewd
56. Test transaction opens a connection
57. Puma connects on the same connection Test transaction opens a connection
58. Plumbing
59. # In actionpack/lib/action_dispatch/system_test_case.rb module ActionDispatch class SystemTestCase < IntegrationTest def initialize(*) # :nodoc: super self.class.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end
60. # In actionpack/lib/action_dispatch/system_test_case.rb module ActionDispatch class SystemTestCase < IntegrationTest def initialize(*) # :nodoc: super self.class.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end
61. # In actionpack/lib/action_dispatch/system_test_case.rb module ActionDispatch class SystemTestCase < IntegrationTest def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run end […]
62. # In actionpack/lib/action_dispatch/system_test_case.rb module ActionDispatch class SystemTestCase < IntegrationTest def self.driven_by(driver, using: :chrome, screen_size: [1400, 1400], options: {}) @driver = SystemTesting::Driver.new(driver, using: using, screen_size: screen_size) end driven_by :selenium end SystemTestCase.start_application end
63. # In action_dispatch/system_testing/driver.rb module ActionDispatch module SystemTesting class Driver # :nodoc: def initialize(name, **options) @name = name @browser = options[:using] @screen_size = options[:screen_size] @options = options[:options] end def use register if selenium? setup end
64. # In actionpack/lib/action_dispatch/system_test_case.rb module ActionDispatch class SystemTestCase < IntegrationTest def initialize(*) # :nodoc: super self.class.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end
65. # In action_dispatch/system_testing/driver.rb module ActionDispatch module SystemTesting class Driver # :nodoc: def use register unless rack_test? setup end private def rack_test? @name == :rack_test end […]
66. # In action_dispatch/system_testing/driver.rb def register Capybara.register_driver @name do |app| case @name when :selenium then register_selenium(app) when :poltergeist then register_poltergeist(app) when :webkit then register_webkit(app) end end end
67. # In action_dispatch/system_testing/driver.rb def register Capybara.register_driver @name do |app| Capybara::Selenium::Driver.new(app, { browser: @browser }.merge(@options)) .tap do |driver| driver.browser.manage.window.size = Selenium::WebDriver::Dimension.new(*@screen_size) end end end
68. # In action_dispatch/system_testing/driver.rb module ActionDispatch module SystemTesting class Driver # :nodoc: def use register if selenium? setup end private def selenium? @name == :selenium end […]
69. # In action_dispatch/system_testing/driver.rb module ActionDispatch module SystemTesting class Driver # :nodoc: private def setup Capybara.current_driver = @name end end end end
70. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run BUILDING Open Source Features
71. Public Work
72. Feels like everyone is judging you
74. Stakeholders
77. $%&' ()*+ ,-./
78. $%&' ()*+ ,-./ 70
79. $%&' ()*+ ,-./ Perfect?
80. Consensus is the enemy of vision
81. Dealing with multiple stakeholders
82. Manage expectations
83. Know who you are building the feature for
84. Be open to change
85. Open source doesn’t work without contributors
86. Build a foundation for others to work off of
87. Thanks @twapole
88. Thanks @robin850
89. Thanks @mtsmfm & @lucasmazza
90. Thanks @renchap
91. Open source doesn’t work without contributors
92. Open source doesn’t work without you
93. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run ¡Muchas gracias RubyConf Colombia!
94. module ActionDispatch class SystemTestCase < IntegrationTest include Capybara::DSL include Capybara::Minitest::Assertions include SystemTesting::TestHelpers::SetupAndTeardown include SystemTesting::TestHelpers::ScreenshotHelper def initialize(*) # :nodoc: super self.class.superclass.driver.use end def self.start_application # :nodoc: Capybara.app = Rack::Builder.new do map "/" do run Rails.application end end SystemTesting::Server.new.run Find me everywhere @eileencodes