title: Why does rubocop's Rails/FilePath cop recommend Rails.root.join
body: <p>I have the following line in my code:</p>
  
  <pre><code>require "#{Rails.root}/config/environments/production.rb"
  </code></pre>
  
  <p>Rubocop's <code>Rails/FilePath</code> cop recommends I change it to:</p>
  
  <pre><code>require Rails.root.join('config', 'environments', 'production.rb')
  </code></pre>
  
  <p>Why?  The former is more compact, appears faster and is arguably more readable.</p>