METRIC+: A Metamorphic Relation Identification Technique Based on Input plus Output Domains

Metamorphic testing is well known for its ability to alleviate the oracle problem in software testing. The main idea ofmetamorphic testing is to test a software system by checking whether each identified metamorphic relation (MR) holds among severalexecutions. In this regard, identifying MRs is an essential task in metamorphic testing. In view of the importance of this identificationtask, METRIC (METamorphic Relation Identification based on Category-choice framework) was developed to help software testersidentify MRs from a given set of complete test frames. However, during MR identification, METRIC primarily focuses on the inputdomain without sufficient attention given to the output domain, thereby hindering the effectiveness of METRIC. Inspired by this problem,we have extended METRIC into METRIC + by incorporating the information derived from the output domain for MR identification. A toolimplementing METRIC + has also been developed. Two rounds of experiments, involving four real-life specifications, have beenconducted to evaluate the effectiveness and efficiency of METRIC + . The results have confirmed that METRIC + is highly effective andefficient in MR identification. Additional experiments have been performed to compare the fault detection capability of the MRsgenerated by METRIC + and those bymMT (another MR identification technique). The comparison results have confirmed that the MRsgenerated by METRIC + are highly effective in fault detection.