Detecting double faults on term and literal in boolean expressions

Fault-based testing aims at selecting test cases to guarantee the detection of certain prescribed faults in programs. The detection conditions of single faults have been studied and used in areas like developing test case selection strategies, establishing relationships between faults and investigating the fault coupling effect. It is common, however, for programmers to commit more than one fault. Our previous studies on the detection conditions of faults in Boolean expressions show that (1) some test case selection strategies developed for the detection of single faults can also detect all double faults related to terms, but (2) these strategies cannot guarantee to detect all double faults related to literals. This paper supplements our previous studies and completes our series of analysis of the detection condition of all double fault classes in Boolean expressions. Here we consider the fault detection conditions of combinations of two single faults, in which one is related to term and the other is related to literal. We find that all such faulty expressions, except two, can be detected by some test case selection strategies for single fault detection. Moreover, the two exception faulty expressions can be detected by existing strategies when used together with a supplementary strategy which we earlier developed to detect double literal faults.