app/views/posts/index.html.erb
<h1>
<% if params[:search].present? %>
Post Search: "<%= params[:search] %>"
<% else %>
Latest Posts
<% end %>
</h1>
<% if @posts.size == 0 %>
<div class="alert alert-info">
<button type="button" class="close" data-dismiss="alert">×</button>
<span>No result found</span>
</div>
<% end %>
<%= render 'list' %>