Abstract
This paper proposes a test sequence generation method for testing the conformance of a protocol implementation to its specification in a remote testing system where both external synchronization and input/output operation costs are taken into consideration. The method consists of a set of transformation rules that constructs a duplexU diagraph from a given finite state machine (FSM) representation of a protocol specification; and a heuristic algorithm that finds 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 minimum-cost test sequence. The X.25 DTE and ISO Class O 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 generated from the Q.931 Network-side protocol is shown to be the cost sum of an input/output operation and an external synchronization operation.