Specification & Description Language (SDL) allows a developer to express software design as an interacting set of independent finite state machines. As such, it is well suited to the development of event-driven, multi-tasking software applications. Message Sequence Chart (MSC) is a graphical language used for the specification and description of the communication behavior among system components by means of message interchange. MSC is used to document the interactions between finite state machines and it is included in most SDL toolsets.
The article is devoted to MSC testing: the testing of self-standing SDL model by applying a set of MSC-described scenarios. The questions of where MSC testing is applicable and where it will take no effect in comparison with box testing are considered. The article deal with problems of MSC testing efficiency measurement and tracking, its methods, benefits and constraint. Such questions as MSC coding style influence on readability and maintainability of tests, real statistics of MSC testing usage analyzing and FMEA-based tools (Failure Mode & Defects Analysis) that is used for tracking of MSC found defects are considered also.