As you may be aware, assert_select spits out annoying warnings when testing XML output that contains auto-closing HTML tags. I submitted a patch fix the issue a few weeks ago.

If you need this fix and don’t want to patch Rails directly, you can monkey patch Rails. But it’s a little tricky because the module is re-loaded during testing after environment.rb is executed. Therefore, the usual method of putting a patch in lib/ and requiring it from environment.rb doesn’t work.

The patch is simply:

module ActionController::TestProcess
  def html_document  
    xml = @response.content_type =~ /xml$/
    @html_document ||= HTML::Document.new(@response.body, false, xml)
  end
end

However it needs to be placed after the require 'test_help' statement in test/test_helper.rb or it will be overwritten.