Enable HTML Source snapshot in RSpec's system specs

system_spec_html_screenshot.rb

return unless Rails.env.test?

require 'highline'
require "action_dispatch/system_testing/test_helpers/screenshot_helper"

module ActionDispatch
  module SystemTesting
    module TestHelpers
      module ScreenshotHelper
        module HtmlSaver
          private

          def rack_test?
            Capybara.current_driver == :rack_test
          end

          def image_path
            # Rails 6+
            @image_path ||= absolute_image_path.to_s
          end

          def html_path
            @html_path ||= absolute_html_path.to_s
          end

          def absolute_html_path
            Rails.root.join("tmp/screenshots/#{image_name}.html")
          end

          def save_image
            super unless rack_test?
            page.save_page(absolute_html_path)
          end

          def cli
            @cli ||= HighLine.new
          end

          def display_image
            message =
              if rack_test?
                <<~EOS
                [HTML Source]: file://#{html_path}
                EOS
              else
                super.sub(/^\[Screenshot\].*\n/, "[Screenshot]: file://#{image_path}\n[HTML Source]: file://#{html_path}\n")
              end
            cli.color(message, :yellow)
          end

          def supports_screenshot?
            true
          end
        end

        prepend HtmlSaver
      end
    end
  end
end