RailsConf 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 Hi! I’m 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 whole 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
19. 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?
20. Integration tests were slowww….
23. Yo, can you make my system test promise come true?
24. I had never used Capybara before
25. 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
26. 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
27. Optimize for programmer happiness
28. 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
29. There is zero configuration required to use Capybara with Rails 5.1
30. require 'test_helper' class ApplicationSystemTestCase < ActionDispatch::SystemTestCase driven_by :selenium, using: :chrome, screen_size: [1400, 1400] end
31. Value integrated systems
32. Rails as a whole now addresses system testing
33. Progress over stability
34. When system tests were merged there were a few known bugs
35. 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
36. Config defaults: Why Selenium?
37. Selenium doesn’t require system installs
38. Can see the tests running in the browser
39. Better for beginners learning Rails and Capybara
40. driven_by :selenium Driver Options
41. driven_by :poltergeist Driver Options
42. Config defaults: Why Chrome?
43. Chrome is widely used
44. For awhile, Firefox was broken with Selenium
45. driven_by :selenium, using: :chrome Driver Options
46. driven_by :selenium, using: :firefox Driver Options
47. Driver Options driven_by :selenium, using: :firefox
 screen_size: [1400, 1400]
48. Driver Options driven_by :selenium, using: :firefox
 options: { url: "http://chrome:4444/hub" }
49. Config defaults: Failure Screenshots
50. def after_teardown take_failed_screenshot Capybara.reset_sessions! super end Driver Options
51. test "the page contains users" do visit users_path take_screenshot assert_selector "h1", text: "Arya" end Take a Screenshot
52. Database Cleaner not required
53. Test transaction opens a connection
54. Puma opens a second connection Test transaction opens a connection
55. The first connection can’t see the data inserted on the second connection
57. I asked for help from @tenderlove & @matthewd
58. Puma connects on the same connection Test transaction opens a connection
59. Plumbing
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 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
62. # 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 […]
63. # 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
64. # 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
65. # 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
66. # 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 […]
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. $%&' ()*+ ,-./
80. $%&' ()*+ ,-./ Perfect?
81. Respecting 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 Thank you RailsConf!
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