SOME GRAPHICAL AIDS FOR DECIDING WHEN TO STOP TESTING SOFTWARE

Developers of large software systems must decide how much software should be tested before releasing it. We consider an explicit tradeoff between the costs of testing and releasing. The former may include the opportunity cost of continued testing, and the latter may include the cost of customer dissatisfaction and of fixing faults found in the field. Exact stopping rules were obtained by the authors, in a previous paper [1], under the assumption that the distribution of the fault finding rate is known. Here we consider two important variants where the fault finding distribution is not completely known. They are: i) the distribution is exponential with unknown mean, and ii) the distribution is locally exponential with rate changing smoothly over time. We present new procedures for both cases. In case i) we also show how to incorporate information from related projects and subjective inputs. We propose several new graphical procedures which are easy to implement, and we illustrate these for data from a large telecommunications software system. © 1990 IEEE