Save/show browser logs (Chome + Selenium + Capybara + Rails)

application_system_test_case.rb

class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
  Capybara.register_driver :chrome_headless do |app|
    client = Selenium::WebDriver::Remote::Http::Default.new
    client.read_timeout = ENV.fetch("SELENIUM_READ_TIMEOUT", 120).to_i

    options = Selenium::WebDriver::Chrome::Options.new
    options.add_argument('--headless=new') if ENV["HEADLESS"] != "false"
    options.add_argument('--disable-extensions')
    options.add_argument('--disable-gpu')
    options.add_option("goog:loggingPrefs", { browser: "ALL" })

    if ENV["CI"].present? || ENV["CODESPACES"].present?
      options.add_argument('--no-sandbox')
      options.add_argument('--disable-dev-shm-usage')
    end

    driver_arguments = {
      http_client: client,
      browser: :chrome,
      # List https://chromedriver.chromium.org/capabilities
      options: options,
      clear_local_storage: true,
      clear_session_storage: true
    }
    
    Capybara::Selenium::Driver.new(app, **driver_arguments)
  end

  def self.browser_logger
    @browser_logger ||= Logger.new(
      Rails.root.join("log", "browser.log"),
      formatter: proc { |_, _, _, msg| msg }
    )
  end

  def self.logger_formatter
    @logger_formatter ||= Logger::Formatter.new
  end

  def browser_logger
    self.class.browser_logger
  end

  def logger_formatter
    self.class.logger_formatter
  end

  def before_teardown
    # Get browser console logs.
    #
    # You can test it using:
    #  — `execute_script("console.error('This is error')")`.
    #  — `execute_script("console.info('This is info')")`.
    #  — `execute_script("console.log('This is log')")`.
    browser_logs = page.driver.browser.logs.get(:browser)

    browser_logs.each do |log|
      browser_logger.unknown do
        # Keep microseconds and local machine timezone
        seconds, microseconds = log.timestamp.divmod(1000)
        time = Time.at(seconds, microseconds * 1000)

        # Write log message with test name
        logger_formatter.call(log.level, time, name, log.message)
      end
    end

    super
  end

  def browser_logs
    page.driver.browser.manage.logs.get(:browser)
  end
end