A Rails view anti-pattern is that they very quickly turn into a nasty tangle of conditional html blocks.
<code class="ruby"> <% if logged_in? && @user == current_user %>
Simple example, but what is the intention of that code? Why are you really checking for? Give that state a name.
Change that to:
<code class="ruby"> def viewing_own_profile(user) logged_in? && user == current_user end <% if viewing_own_profile(@user) %>
Now you can test that helper method without resorting to rendering a view and parsing it to check if elements exist, the state you care about is named and the intention is clear.