candidate_for_layout?

# File actionpack/lib/action_controller/layout.rb, line 264
      def candidate_for_layout?(options)
        template = options[:template] || default_template(options[:action])
        if options.values_at(:text, :xml, :json, :file, :inline, :partial, :nothing, :update).compact.empty?
          begin
            template_object = self.view_paths.find_template(template, default_template_format)
            # this restores the behavior from 2.2.2, where response.template.template_format was reset
            # to :html for :js requests with a matching html template.
            # see v2.2.2, ActionView::Base, lines 328-330
            @real_format = :html if response.template.template_format == :js && template_object.format == "html"
            !template_object.exempt_from_layout?
          rescue ActionView::MissingTemplate
            true
          end
        end
      rescue ActionView::MissingTemplate
        false
      end