rails--rails/actionpack/lib/action_dispatch/testing/assertions.rb

require "rails-dom-testing"

module ActionDispatch
  module Assertions
    autoload :ResponseAssertions, "action_dispatch/testing/assertions/response"
    autoload :RoutingAssertions, "action_dispatch/testing/assertions/routing"

    extend ActiveSupport::Concern

    include ResponseAssertions
    include RoutingAssertions
    include Rails::Dom::Testing::Assertions

    def html_document
      @html_document ||= if @response.content_type.to_s =~ /xml\z/
        Nokogiri::XML::Document.parse(@response.body)
      else
        Nokogiri::HTML::Document.parse(@response.body)
      end
    end
  end
end