Wait for dynamic content with capybara feature spec

feature_spec_helper.rb

# wait_for_content 'Submit'
# wait_for_content 'Submit', selector: '.super-button'
# wait_for_content 'Submit', selector: 'form .super-button'
# wait_for_content 'Message', timeout_s: 5
# wait_for_content 'Messages?', timeout_s: 5
# wait_for_content '[ck]lass(es)?'
# wait_for_content 'Thanks' do
#   puts 'Waiting...'
# end
#
def wait_for_content(content_js_regexp, options={}, &block)
  begin
    page.document.synchronize(options[:timeout_s] || Capybara.default_wait_time) do
      selector = options[:selector] || 'html'
      js_code = "(new RegExp('#{content_js_regexp}')).test($('#{selector}').html())"
      found = page.evaluate_script(js_code)
      if found
        true
      else
        yield if block_given?
        false
      end
    end
  rescue Timeout::Error => e
    puts "---------------------------------------- #wait_for_content: #{content_js_regexp}"
    puts "---------------------------------------- e: Timeout::Error"
    puts e.inspect rescue nil
    puts "---------------------------------------- page.response_headers:"
    puts page.response_headers rescue nil
    puts "---------------------------------------- page.text:"
    puts page.text rescue nil
    puts "---------------------------------------- page.html:"
    puts page.html rescue nil
    save_page_response = save_page rescue nil
    puts "---------------------------------------- save_page: #{save_page_response}"
    puts "---------------------------------------- //"
    raise
  end
end