Statistical testing for cleanroom software engineering

Cleanroom software engineering requires statistical testing by an independent agent for the purpose of certifying software quality. Statistical software testing is a formal process that involves sampling from the intended usage environment and the precise measurement of properties of random variables inherent in such a statistical experiment. The first step in conducting a statistical test is to determine the usage distribution for the software in its intended environment. This distribution is the basis for a random generator of test sequences for the software. In order to achieve this distribution, a usage analysis is performed using the software specification and any available usage information. The usage analysis consists of a top down, structural investigation of the specification document that establishes a set of usage states and defines an ordering on this set. The paper describes in detail the usage analysis and inference procedure including various computations on the ensuing Markov chains. Stopping criteria are developed and a discrete software reliability model is presented