Link appears in the browser, but the test says it's not there

_article.html.erb

<% if user_signed_in? %>
  <% if current_user.id == article.author.id %>
    <%= link_to 'Edit article', edit_article_path(article) %>
  <% end %>
<% end %>

articles_pages_spec.rb

let(:user) { Fabricate(:user) }
before do
  visit new_user_session_path
  fill_in 'Email', :with => user.email
  fill_in 'Password', :with => user.password
  click_button 'Sign in'
end

describe 'when user has a self-authored article' do
  let(:article) { Fabricate(:article, :author_id => user.id) }
  before { visit articles_path }
  it { should have_link('Edit article', :href => edit_article_path(article)) }
end

new.html.erb

<% provide(:title, 'Articles') %>
<h1>Articles</h1>
<% if user_signed_in? %>
  <%= link_to 'Post article', new_article_path %>
<% end %>

<%= render @articles %>

<%= will_paginate %>