Improving logic-based testing

Logic-based testers design tests from logical expressions that appear in software artifacts such as source code, design models, and requirements specifications. This paper presents three improvements to logic-based test design. First, in the context of mutation testing, we present fault hierarchies for the six relational operators. Applying the ROR mutation operator causes each relational operator to generate seven mutants per clause. The fault hierarchies show that only three of these seven mutants are needed. Second, we show how to bring the power of the ROR operator to logic-based test criteria such as the widely used Multiple Condition-Decision Coverage (MCDC) test criterion. Third, we present theoretical results supported by empirical data that show that the more recent coverage criterion of minimal-MUMCUT can find significantly more faults than MCDC. The paper has three specific recommendations: (1) Change the way the ROR mutation operator is defined in existing and future mutation systems; (2) Augment logic-based test criteria to incorporate relational operator replacement from mutation; (3) Replace the use of MCDC with minimal-MUMCUT, both in practice and in standards documents like FAA-DO178B.