Make Chromedriver truly headless

[gabebw]

When I use Suspenders' configuration on a new project, JavaScript tests open up the Chrome app in a real window (i.e. not headless).

When using the configuration in this commit, Chrome quietly bounces once, in the taskbar (on macOS), and does not create a window.

[composerinteralia]

I just started a new project and was frustrated to see my tests open up a non-headless chrome. I was excited to see this PR, but unfortunately the change had no effect for me. Was there anything else you needed to do to get this working?

[gabebw]

Maybe the version of Chrome matters?

I'm using:

• Chrome 75.0.3770.100 (Official Build) (64-bit) (taken from chrome://version/)
• macOS Mojave 10.14.5

There is technically slightly more stuff in my spec/support/chromedriver.rb, e.g the changes from #981 and #983, though I think that doesn't affect it. Regardless, here is my full spec/support/chromedriver.rb:

require "selenium/webdriver"

Capybara.register_driver :chrome do |app|
  Capybara::Selenium::Driver.new(app, browser: :chrome)
end

Capybara.register_driver :headless_chrome do |app|
  options = ::Selenium::WebDriver::Chrome::Options.new
  options.headless!
  # Set a big (15" MBP retina resolution) window size so that
  # `save_and_open_screenshot` captures the whole page.
  options.add_argument '--window-size=1680,1050'

  capabilities = Selenium::WebDriver::Remote::Capabilities.chrome(
    chromeOptions: { args: %w(headless disable-gpu) },
    loggingPrefs: {
      browser: 'ALL'
    }
  )

  Capybara::Selenium::Driver.new app,
    browser: :chrome,
    options: options,
    desired_capabilities: capabilities
end

Capybara.javascript_driver = :headless_chrome

# Silence Puma's startup message in specs
# https://github.com/rspec/rspec-rails/issues/1897
Capybara.server = :puma, { Silent: true }

[delphaber]

I can confirm that this PR makes my tests go headless. Anyway, I remember I was able to run them headless without this PR, but now I need this PR.

So maybe it depends on a newever Chrome version?

I'm wondering what headless means in chromeOptions: { args: %w(headless disable-gpu) },. Do we need it?

Google Chrome	75.0.3770.100 (Build ufficiale) (a 64 bit)
Revisione	cd0b15c8b6a4e70c44e27f35c37a4029bad3e3b0-refs/branch-heads/3770@{#1033}
Sistema operativo	Mac OS X 10.14.5

[composerinteralia]

OK, I updated all the things and this is working for me now. After a bit of digging, I am not convinced the chromeOptions: { args: %w(headless disable-gpu) }, is doing anything anymore. It looks like the key actually changed to goog:chromeOptions in SeleniumHQ/selenium@0ba8188#diff-6d36ad83184bcee9c97af166e99e3f4b.
I tried changing that key without including any of the changes in this PR and it did make chromedriver headless.

It may also be fine to lose the disable-gpu options. I am not sure exactly why that option was there in the first place, but Selenium was using it as a workaround for windows and removed it in SeleniumHQ/selenium#6943.

[gabebw]

I confirm that on macOS, with Chrome 75, using just headless! runs the tests in actual headless Chrome. I've updated this PR appropriately, in 8f33976.

[composerinteralia]

Thanks!