Minimum-Cost Synchronizable Test Sequence Generation via the DuplexU Digraph

This paper proposes a test sequence generation method for testing the coNormance of a protocol implementation to its specification in a remote testing system where both external synchronization and inputloutput operation costs are taken into consideration. The method consists of a set of transformation rules that constructs a duplexu digraph from a given finite state machine (FSM) representation of a protocol specification; and a heuristic algorithm that furdr a rural postman tour in the duplexu digraph to generate a synchronizable test sequence utilizing multiple UIO sequences. If the protocol satisfies a specific property, the heuristic algorithm yields a minimumcost test sequence. The X.25 DTE and I S 0 Class 0 Transport protocols are proved to possess this specific property. Otherwise, the heuristic algorithm yields a test sequence whose cost is within a bound from the cost of the minimum-cost test sequence. The bound for the test sequence generatedfrom the Q.931 Networksi& protocol is shown to be the cost sum of an inputloutput operation and an external synchronization operation.