The universal safeness of test allocation strategies for partition testing

Given a specification, a partition testing strategy is said to be safe for a program if it is not less probable of detecting at least one failure than random testing, and universally safe, if it is safe for every program. The proportional sampling strategy (PSS) has previously been proved to be univ ersally safe. This paper extends previous results by proving that PSS is ac tually the only universally safe test allocation strategy for partition tes ting, thereby settling an open problem in the search for universally safe s trategies. Despite this, we show that a close approximation to PSS may stil l be safe for most programs. We also discuss the practical implications of this result. (C) 2000 Elsevier Science Inc. All rights reserved.