Enable to show css & js on save_and_open_page

Gemfile

gem 'guard-rails-assets'

Guardfile

guard 'rails-assets', run_on: :change do
  watch(%r{^app/assets/.+$})
end

config/environments/test.rb

  # guard-rails-assets
  config.assets.prefix = 'assets-test'

  # capybara
  config.action_controller.asset_host = "file://#{::Rails.root}/public"