The idea of testing is to modify the code so that it throws an Error exception and then confirm that we only see a failed task without any further uncaught exceptions. Modify the source code of the file mod/workshop/allocation/scheduled/classes/task/cron_task.php: Around the line 59 change the name of the method "get_records_sql()" to something non-existing such as "muhahaha_get_records_sql()" Run the task: $ sudo -u apache php admin/cli/scheduled_task.php --execute='\workshopallocation_scheduled\task\cron_task' TEST Check that the output contains something like "Scheduled task failed - Call to undefined method" TEST Confirm there is no other exception handling output such as "Default exception handler: Exception", no error related to database locking etc.