Usability challenges in exception handling

Two language mechanisms are presented and assessed for assisting understanding of exception complexity. First, passive and active exception assertions dynamically check if the reason for an exception raise matches with the purpose of a matching handler. A passive assertion is a check when an exception propagates out of a block it guards. The active form adds probabilistically injection of exceptions to provide more comprehensive testing. Second, runtime exception information is logged for dynamic query to check current handling status and provide a history of exceptional events.