SystemTesting::Driver can register capybara-webkit and poltergeist

[mariochavez]

drivers.

When using driver_by with capybara-webkit or poltergeist,
SystemTesting::Driver will register the driver while passing
screen_size and options parameteres.

options could contain any option supported by the underlying driver.

This PR is related to issue #29000

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[eileencodes]

Looking good so far! 👍 Left some comments for changes I'd like to see. Thanks for working on this.

[eileencodes]

Can you make a new private register method and move this case statement inside. Then move the duplicate code from the namespaced register methods into the register method?

def use
  register unless rack_test?
  setup
end

private
  def register
   Capybara.register_driver @name do |app|
    case @name
    etc
  end
end

def register_selenium
...
end

etc

[eileencodes]

What is the if defined?(Capybara::Poltergeist) buying us? This won't load without register getting called and if you don't add the gemfile it will blow up anyway. Otherwise this will silently fail I think.

[eileencodes]

✂️ this extra line.

[eileencodes]

Looks great, thanks!

Can you add an entry to the top of the actionpack CHANGELOG? And then squash your commits into one? I'll merge once those are done. Thanks for working on this!

[mariochavez]

@eileencodes done ! Thanks for your help to get this thru.

[eileencodes]

Backported in c5dd451 because while a feature enhancement it's a very new feature and since this was missing I consider it a 🐛

[sebastianiorga]

Apologies if this is the wrong place to raise this issue, but it's directly caused by this pull request.

Ruby version 2.4.1
Rails version 5.1.2
Capybara version 2.14.4

The changes made in this commit to actionpack/lib/action_dispatch/system_testing/driver.rb break the ability to register Capybara drivers not named [:selenium, :poltergeist, :webkit].

Because ActionDispatch::SystemTesting::Driver#driver now gets called UNLESS name is :rack_test, it ends up overwriting custom Capybara drivers setup in RAILS_ROOT/test/application_system_test_case.rb with nil(since the case statement in register can only handle 3 keys.

For instance, the code below sets up headless_chrome as a system test driver:

# test/application_system_test_case.rb
require 'test_helper'
require 'capybara'
# require 'capybara/poltergeist'

ENV['RAILS_SYSTEM_TESTING_SCREENSHOT'] = 'simple'

class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
  # driven_by :selenium, using: :chrome, screen_size: [1400, 1400]
  Capybara.register_driver(:headless_chrome) do |app|
    capabilities = Selenium::WebDriver::Remote::Capabilities.chrome(
      chromeOptions: { args: %w[headless disable-gpu window-size=1920x1080] }
    )

    Capybara::Selenium::Driver.new(
      app,
      browser: :chrome,
      desired_capabilities: capabilities
    )
  end
  driven_by :headless_chrome
  # Rack::Test
  # driven_by :rack_test

  # capybara-webkit
  # Capybara::Webkit.configure do |config|
  #   config.raise_javascript_errors = false
  # end
  # driven_by :webkit

  # Poltergeist
  # Capybara.register_driver :poltergeist do |app|
  #   Capybara::Poltergeist::Driver.new(app, js_errors: true)
  # end
  # driven_by :poltergeist
end

This causes a nil error in Capybara::Session#driver since driver ends up being set to nil for the :headless_chrome mode.

Super hacky fix is to monkey patch register:

# test/application_system_test_case.rb
require 'test_helper'
require 'capybara'
# require 'capybara/poltergeist'

ENV['RAILS_SYSTEM_TESTING_SCREENSHOT'] = 'simple'
ActionDispatch::SystemTestCase.driver
class ActionDispatch::SystemTesting::Driver # :nodoc:
  def register
    return unless [:selenium, :poltergeist, :webkit].include?(@name)

    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
end

class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
...

This is obviously not the way to go about things. I'm not sure modifying ActionDispatch::SystemTesting::Driver#register with that guard clause is the right solution either. After all: what makes those 3 options special? And if they are special there should be some single source of truth where they are declared with the case statement and other areas in the code referencing them.

Possibly a solution involves some sort of polymorphism, with a fallback that does nothing when the user manually registered the capybara driver they want to use?

Again, apologies if this is the wrong place for this comment.

[eileencodes]

@sebastianiorga can you open a new issue with these details and reference this PR?