people_helper.rb

module PeopleHelper
  def subnavigation
    items = []
    items << link_to('Person List', people_path, :class => 'list') unless params[:action].eql?('index')
    items << link_to('Register Person', new_user_registration_path, :class => 'new') unless params[:action].eql?('new') or params[:action].eql?('show')
    items << link_to('Edit Person', edit_person_path, :class => 'edit') if params[:action].eql?('show')
    items << link_to('Delete Person', person_path, :confirm => 'Are you sure?', :method => :delete, :class => 'delete') if params[:action].eql?('show')
    items = content_tag(:ul, items.collect{|n| content_tag(:li, n)})
    content_tag(:div, items, :id => 'subnavigation')
  end
end

people_helper_spec.rb

require 'spec_helper'

describe PeopleHelper do
    it "subnavigation should contain links to edit and delete on a show action" do
    assigns[:params] = {:action => 'show', :id => 1}
    subnavigation = helper.subnavigation
    subnavigation.should have_tag('ul') do
      with_tag('li', :text => /Edit Person/) { with_tag('a', :href => edit_person_path(:id => 1)) }
      with_tag('li', :text => /Delete Person/) { with_tag('a', :href => person_path(:id => 1, :method => :delete)) }
    end
  end

end

whoops.txt

edit_person_url failed to generate from {:action=>"edit", :controller=>"people"} - you may have ambiguous routes, or you may need to supply additional parameters for this route.  content_url has the following required parameters: ["people", :id, "edit"] - are they all satisfied?
(eval):16:in `edit_person_path'