On Detecting Double Literal Faults in Boolean Expressions

Abstract

Fault-based testing aims at selecting test cases to detect hypothesized faults in a program.When a program contains a fault so that it behaves differently from as is expected, test cases that satisfy the detection condition of the fault will be able to detect it. Detection conditions of single occurrence of hypothesized faults had been studied and used to propose testing strategies and investigate relationships between different types of faults. As software developers may make several mistakes during software development, multiple faults may occur in a program. In this paper, we report our study in detection conditions of double occurrences of faults related to literals in a Boolean expression. This leads to some interesting observations. Some previous studies in double fault discarded equivalent mutants caused by a single fault. However, we observe that such equivalent mutants may give rise to non-equivalent double fault mutants, and hence, cannot be discarded. Moreover, we have developed several supplementary test case selection strategies to detect double faults that cannot be detected by existing test case selection strategies which aim at single-fault detection.