Mutation testing aims to evaluate the fault detection capability of a test suite. This evaluation substitutes faults with mutants by transforming program code to be defective. Evidences of the relationship between the detection rates of mutants and real faults have supported the use of mutants. It has also been known that the test suite size was a significant factor affecting the relationship. Our study revealed that the selection of the mutated code was another factor affecting the relationship. We generated mutants by transforming the code modified to fix defects, while the modified code was located at three granularity levels. The experiments conducted on the defects4j dataset demonstrated that the granularity level caused a significant difference in the relationship; the detection rate of mutants was more strongly correlated with and more indicative of the fault detection capability at a fine level than at a coarse level. Moreover, the influence of the test suite size was different at each granularity level. These findings implied a strong correlation between the detection rates of mutants and real faults, independently of test suite size, when the error-prone code was located precisely.

中文翻译：

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就突变代码研究突变与实际错误之间的关系

突变测试旨在评估测试套件的故障检测能力。该评估通过将程序代码转换为有缺陷的方式来用突变体替代错误。突变体的检测率与实际故障之间关系的证据支持使用突变体。众所周知，测试套件的大小是影响这种关系的一个重要因素。我们的研究表明，突变代码的选择是影响这种关系的另一个因素。我们通过转换修改后的代码来修复缺陷来生成突变体，而修改后的代码位于三个粒度级别。在defects4j数据集上进行的实验表明，粒度级别导致了关系的显着差异；突变体的检测率在精细级别与粗略级别的故障检测能力相关性更强，更能表明故障检测能力。此外，测试套件大小的影响在每个粒度级别上都是不同的。这些发现表明，当精确定位容易出错的代码时，突变体的检测率与实际故障之间存在很强的相关性，而与测试套件的大小无关。