title: What does before_action returning false do in Rails 4?
body: <p>I am reading the "Agile Web Development with Rails 4", on pag. 338 it says: </p>
  
  <blockquote>
    <p>[...] Callbacks can be passive, monitoring activity performed by a controller. They can also take a more active part in request handling. If a before action callback returns false, then processing of the callback chain terminates, and the action is not run. [...]</p>
  </blockquote>
  
  <p>Now my doubt is the following: here <a href="https://stackoverflow.com/questions/20120485/how-to-execute-an-action-if-the-before-action-returns-false">how to execute an action if the before_action returns false</a> it was told that the goal of the before_action is to prepare something before the action is executed, if it returns false it doesn't mean that the action is not run, but according the book it is right so...so I am getting a little bit confused.</p>
  
  <p>If I'm trying the following</p>
  
  <pre><code>class ProductsController &lt; ApplicationController
  before_action :test
  
    def index
      @products = Product.all
    end
  
  
    private
  
      def test
        return false
      end
  end
  </code></pre>
  
  <p>But the action is executed, when I call <code>/products</code> I do not get any error and the page shows up just fine</p>