A New Approach To Test Sequence Derivation Based on External Behavior Expression (EBE)

This paper presents a new approach to test sequence derivation from formal protocol specifications for protocol conformance testing. The approach is based on a model of External Behaviour Expression (EBE) which specifies only the external behaviour of a protocol in terms of the input/output sequences and their logical (function and predicate) relations, and can be obtained from formal protocol specifications in either Estelle or LOTOS. A basic test derivation theory is defined for the purpose of formalizing test sequence derivation strategies. Based on the EBE of a protocol, a test sequence derivation method is proposed to identify associations between inputs and outputs through the interaction paths and their I/O subpaths. Generic Test Cases generated from these I/O subpaths are based on specific testing purposes. Abstract Test Cases are selected in terms of particular test methods and additional requirements. Comparison to other existing schemes shows the method proposed here is simple and concise, and the resulting set of test sequences is complete and effective. It is our belief that this approach to test sequence derivation can provide the basis of a formalized framework for protocol conformance testing.