Hi, Yesterday we had quite a discussion on IRC which is summed up http://groups.drupal.org/node/10957 . Basically, mock functions were voted down as tests based on them takes too much developer resources to write and maintain. Instead, we are writing functional testing on an API level as described on http://drupal.org/node/30008 , for example: $this->assertEqual(l('Some page', 'node/34', array('class' => 'foobar')), '<a href="/node/34" class="foobar">some page</a>'); This test presumes and verifies somewhat that every function l calls is working correctly. Whether this still can be called unit testing or not is a pointless academic debate :) I expect that a number of tasks will be placed in the Drupal issue queue telling the community which tests are to be written. When this happens, I guess another email will land here and also I guess at various other places... I also plan to hold a 'testing hour' every single day starting probably next week. Stay tuned! Karoly Negyesi