application_helper.rb

module ApplicationHelper

  # Generates a title, with a padlock if the category being shown is
  # a proprietary dataset
  def commercially_aware_title(result)
    
    #padlock_string = content_tag(:span, "x", :class => "padlock") # this DON'T work
    padlock_string = content_tag :span, "x".html_safe, :class => "padlock" # this DOES work

    result.public?(session[:project]) ? result.title : "#{result.title} #{padlock_string}".html_safe                    
  end

end

application_helper_spec.rb

  context 'displaying commercial links to pages' do

    it "adds a padlock to titles for proprietary datasets" do

      result = flexmock("result", 
        :public? => false,
        :title => "A category title"
      )

    helper.commercially_aware_title(result).should match 'A category title <span class="padlock">&#120;</span>'

    end

  end