I. Introduction
Software reliability is an attribute of software qualities to ensure that software can continuously provide its service without any failure. In particular, quantitative software reliability evaluation is helpful to control software testing, and there have been a variety of approaches of quantitative software reliability evaluation in the past literature. One of the most attractive approaches is a model-based approach that describes software reliability growth phenomena in testing phase. So, if the number of faults in software is finite, then the number of detected faults gradually decreases as testing time elapses. Software reliability model or equivalently software reliability growth model (SRGM) is defined as a stochastic model to represent such software reliability growth phenomena. From the mathematical point of view, non-homogeneous Poisson processes (NHPPs) are commonly used to describe software fault detection processes due to their mathematical tractability. During the last four decades, a number of NHPP-based SRGMs have been proposed [15]. [18]. [19]. [32].