Example to 'disable' layouts in a Rails controller test. Uses an 'empty' layout, which can allow for testing that the the title tag and javascript is properly added...

empty.html.haml

-# Empty layout used as layout replacement for testing...
!!! 5
!= html5_haml_tag(:lang => 'en') do
  %head
    %meta{:content => "text/html; charset=utf-8", "http-equiv" => "Content-Type"}/
    %title=h ((title=yield(:title)).blank?) ? "Contently" : "#{title} : Contently".html_safe
  %body
    =yield
    =yield :javascript
    =yield :jstemplates

posts_controller_spec.rb

describe PostsController

  # Helper method...
  def disable_layout
    @controller.instance_eval do
      def _process_options(options)
        options[:layout] = '/layouts/empty.html'
      end
    end
  end

  # Call the helper method and render views...
  before do
    disable_layout
  end
  render_views

  describe :show do
    ...
  end

end