Chromedriver browser logging for Capybara

browser_logging.rb

# browser_logging.rb will print out the browser log from Chrome
# when running specs with "js: true". This is so we can easily debug
# issues where there are JS errors or other console warnings/error(s), etc.
#
# Output file is: Rails.root/log/browser.log
#
# Note: Nothing will be printed out for non-JS examples.
RSpec.configure do |config|
  browser_log = File.new(Rails.root.join("log/browser.log").to_s, "w")
  browser_log.sync = true

  config.before(:each) do |example|
    if self.class.metadata[:js]
      description = "Example: #{example.full_description}"
      browser_log.puts description, "-"*description.length
    end
  end

  config.after(:each) do |example|
    if self.class.metadata[:js]
      browser_log.puts page.driver.browser.manage.logs.get(:browser)
      browser_log.puts
    end
  end

  config.after(:suite) do
    browser_log.close
  end
end

relevant_bits_of_capybara.rb

# Give us access to browser console logs, see spec/support/browser_logging.rb
logging_preferences = { browser: 'ALL' }

# This env var comes from chromedriver_linux64, used on the TravisCI
chrome_bin = ENV.fetch('CHROME_BIN', nil)
chrome_options = {}
chrome_options[:binary] = chrome_bin if chrome_bin

 # Give us access to browser console logs, see spec/support/browser_logging.rb
logging_preferences = { browser: 'ALL' }

Capybara.register_driver :chrome do |app|
  capabilities = Selenium::WebDriver::Remote::Capabilities.chrome(
    chromeOptions: chrome_options,
    loggingPrefs: logging_preferences
  )

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

Capybara.register_driver :headless_chrome do |app|
  capabilities = Selenium::WebDriver::Remote::Capabilities.chrome(
    chromeOptions: chrome_options.merge(args: %w(headless disable-gpu)),
    loggingPrefs: logging_preferences
  )

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