Testing is a very demanding procedure in software production, that takes a lot of effort, time and resources during both development and maintenance. Moreover, statistical testing is a very costly procedure, especially if high reliability requirements are placed on the software as in safety-critical, or safety-related software cases. The main question is when to stop testing, or how many tests are needed? Singh et al. [49], using the method of the negative binomial, developed a procedure for quantifying the reliability of a module. According to their approach, the number of tests can be computed based on hypothesis testing. We implemented this method for a reliability estimation of a program. In this work, a prototype black-box automated testing tool, called Program Reliability Estimation Tool (PRET) was developed as a statistical test generator and reliability estimation tool based on an operational profile (a proposed testing model) and negative binomial sampling.
