title: Capybara unable to find field "search"
body: <p>I tried setting the id in various parts of the form, as well as wrapping the form in a div with id set to <code>search</code>. The result is always the same. </p>
  
  <h1>spec/features/02_post_spec.rb</h1>
  
  <pre><code>  scenario 'search for post title' do
      fill_post_form(post3)
      fill_in "search", with: post3.title
      click_button("Search")
  
      expect(page).to_not have_content(post1.title)
      expect(page).to_not have_content(post2.title)
      expect(page).to have_content(post3.title)
    end
  </code></pre>
  
  <h1>spec/spec_helper.rb</h1>
  
  <pre><code>def fill_post_form(post)
    visit new_post_path
    fill_in 'Title', with: post.title
    fill_in 'Body', with: post.body
    click_button 'Create Post'
  end
  </code></pre>
  
  <p>This will <code>redirect_to post_path(post)</code></p>
  
  <h1>views/posts/index.html.erb</h1>
  
  <pre><code>&lt;%= form_tag(posts_path, method: :get, class: "block") do %&gt;
    &lt;div class="form-group"&gt;
      &lt;div class="input-group"&gt;
        &lt;%= text_field_tag :search, params[:search], class: "form-control", id: "search" %&gt;
        &lt;span class="input-group-btn"&gt;
          &lt;%= submit_tag "Search", name: nil, class: "btn btn-default" %&gt;
        &lt;/span&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;% end %&gt;
  </code></pre>
  
  <p>Capybara output</p>
  
  <pre><code> Failure/Error: fill_in "search", with: post3.title
  
   Capybara::ElementNotFound:
     Unable to find field "search"
  </code></pre>