TTCN: Towards a Formal Semantics and Validation of Test Suites

TTCN (Tree and Tabular Combined Notation) is the standardized test notation for the description of OSI conformance tests. Since applicability of TTCN is restricted, work on the deenition of concurrent TTCN, an extended version of TTCN for the speciication of test cases for multi party testing, has been started a few years ago. In this paper we discuss diierent approaches for the deenition of an operational semantics of TTCN and concurrent TTCN and we discuss issues related to the validation of (concurrent) TTCN test cases. Because for the validation of test cases a proper semantics deenition is a prerequisite we have developed a semantics deenition which utilizes labelled transition systems as its basic model. The applicability of the model is demonstrated: First, we show how identiied incompletenesses and ambiguities of TTCN can be solved. Second, we develop a validation framework that deenes the necessary machinery for the validation of functional properties of test cases against a formal speciication. We illustrate how validation of proper termination and verdict assignments can be performed and how a test case can be validated against an SDL speciication.