Generation of grey box use cases for personal communication systems using simple design machines.

Abstract

The advantages in representing high level user service scenarios by means of a formal testable design notation are several. Formalized scenarios provide for a more extensive test coverage of designs both from the user perspective and the system perspective when compared to a non formal method such as one employing natural language. Verifying completeness of design by scenario checking is targeted towards catching design errors. We present guidelines for constructing test cases and scenarios which simplify the process and disambiguate the specification. This thesis defines a formal testable design notation called Simple Design Machines (SDM's) (simplification of Design Machines); which lends itself to the semi-automated generation of grey-box use cases. These grey box use cases, when combined with white and black box test cases, provide for a more comprehensive test suite. Thus, SDM's support design for Software Testability. Personal Communication Systems is the application used to validate SDM's. In this thesis, first the need for a testable design language is demonstrated, then different existing testing techniques are reviewed, followed by an overview of the proposed new language (SDM's) and the application used for validation (PCS). SDM's are effective in situations where the system responds to combinations of inputs. Examples illustrating how to construct SDM's for simple applications are then given. We subsequently define a mapping from PCS communication systems to SDM's, walk through the generation of grey box use cases, validate these use cases and measure coverage for the SDM designs. A variety of different tools are assessed into for feasibility with respect to automatic test case generation A prototype of the Symbolic Scenario Selector was implemented in C and tested on PCS. Traces are generated for the SDM's and coverage is measured. Inconsistencies in the specification can be detected as the PCS example demonstrated. Finally, we assess advantages and limitations of the approach based on the case study and other experiences.