A semantic model of program faults

Program faults are artifacts that are widely studied, but there are many aspects of faults that we still do not understand. In addition to the simple fact that one important goal during testing is to cause failures and thereby detect faults, a full understanding of the characteristics of faults is crucial to several research areas in testing. These include fault-based testing, testability, mutation testing, and the comparative evaluation of testing strategies. In this workshop paper, we explore the fundamental nature of faults by looking at the differences between a syntactic and semantic characterization of faults. We offer definitions of these characteristics and explore the differentiation. Specifically, we discuss the concept of "size" of program faults - - the measurement of size provides interesting and useful distinctions between the syntactic and semantic characterization of faults. We use the fault size observations to make several predictions about testing and present preliminary data that supports this model. We also use the model to offer explanations about several questions that have intrigued testing researchers.