title: Undefined variable: $_SESSION
body: <p>I'm getting <code>E_NOTICE</code> errors in a core CakePHP file when it tries to reference a never-set or unset session (<code>cake/libs/cake_session.php line 372</code>):</p>
  
  <pre><code>function read($name = null) {
      if (is_null($name)) {
          return $this-&gt;__returnSessionVars();
      }
      if (empty($name)) {
          return false;
      }
      $result = Set::classicExtract($_SESSION, $name);
  }
  </code></pre>
  
  <p>I've done a search through my code (in the app/ directory) and I can't find references to <code>$_SESSION</code> or <code>session_destroy</code>.  Am I missing anything?</p>
  
  <p>This error shows up when I try to run any unit tests.  Is this...normal?  I've cleared out the <code>cake/</code> directory and replaced it with another one (same version) just to make sure that I hadn't inadvertently modified anything in the core files, but I still get the same error.  I'm not sure if this is just a flaw in the framework or something else.</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>Here are the results of the test run on the command line:</p>
  
  <pre><code>Welcome to CakePHP v1.3.11 Console
  ---------------------------------------------------------------
  App : app
  Path: /var/www/program/app
  ---------------------------------------------------------------
  CakePHP Test Shell
  ---------------------------------------------------------------
  Running app case models/owners_equity
  E_NOTICE: Undefined variable: _SESSION in /var/www/program/cake/libs/cake_session.php on line 372
  E_NOTICE: Undefined variable: _SESSION in /var/www/program/cake/libs/cake_session.php on line 372
  ERROR-&gt;Unexpected PHP error [Undefined variable: _SESSION] severity [E_NOTICE] in [/var/www/program/cake/libs/cake_session.php line 372]
      in testGenerateOwnerWithdrawals
      in BalanceTestCase
      in /var/www/program/app/tests/cases/models/owners_equity.test.php
  
  ERROR-&gt;Unexpected PHP error [Undefined variable: _SESSION] severity [E_NOTICE] in [/var/www/program/cake/libs/cake_session.php line 372]
      in testGenerateOwnerWithdrawals
      in BalanceTestCase
      in /var/www/program/app/tests/cases/models/owners_equity.test.php
  </code></pre>