Having trouble in testing CanCan

_article.html.erb

<% if can? :update, article %>
  <%= link_to 'Edit', edit_article_path(article) %>
<% end %>
<% if can? :destroy, article %>
  <%= link_to 'Destroy', article_path(article), :confirm => 'Are you sure?', :method => :delete %>
<% end %>

ability.rb

class Ability
  include CanCan::Ability

  def initialize(user)
    user ||= User.new # Guest user

    if user.role? :admin
      can :manage, :all
    else
      can :read, :all

      if user.role?(:author)
        can :create, Article
        can :update, Article do |article|
          article.try(:author) == user
        end
        can :destroy, Article do |article|
          article.try(:author) == user
        end
      end
    end
  end
end

article_fabricator.rb

Fabricator(:article) do
  title 'This is a title'
  content 'This is the content'
  author! { Fabricate(:author) }
  categories(:count => 1)
end

articles_pages_spec.rb

before do
  @author = Fabricate(:author)
  visit new_user_session_path
  fill_in 'Email', :with => @author.email
  fill_in 'Password', :with => @author.password
  click_button 'Sign in'
  @article = Fabricate(:article, :author_id => @author.id)
  visit articles_path
end

it { should have_link 'Edit', :href => edit_article_path(@article) }
it { should have_link 'Destroy', :method => :delete, :href => article_path(@article) }

# I keep getting this error
#
# Failure/Error: it { should have_link 'Edit', :href => edit_article_path(@article) }
#       expected link "Edit" to return something
#
# Failure/Error: it { should have_link 'Destroy', :method => :delete, :href => article_path(@article) }
#       expected link "Destroy" to return something
#
# It works in the browser though :(

index.html.erb

<%= render @articles %>

user.rb

class User < ActiveRecord::Base
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  attr_accessible :email, :password, :password_confirmation, :remember_me
  attr_accessible :name, :roles

  has_many :articles, :foreign_key => 'author_id', :dependent => :destroy

  ROLES = %w[admin moderator author]

  def roles=(roles)
    self.roles_mask = (roles & ROLES).map { |r| 2**ROLES.index(r) }.sum
  end

  def roles
    ROLES.reject { |r| ((roles_mask || 0) & 2**ROLES.index(r)).zero? }
  end

  def role?(role)
    roles.include?(role.to_s)
  end
end

user_fabricator.rb

Fabricator(:user) do
  email { sequence(:email) { |i| "user#{i}@example.com" } }
  name { sequence(:name) { |i| "Example User-#{i}" } }
  password 'foobar'
end

Fabricator(:admin, :from => :user) do
  roles ['admin']
end

Fabricator(:author, :from => :user) do
  roles ['author']
end

See https://github.com/terenceponce/devcon/pull/14
Basically the fabricator for :article doesn't have an author_id entry so the :author_id => @author.id is ignored.