Cleansing Test Suites from Coincidental Correctness to Enhance Fault-Localization

Researchers have argued that for failure to be observed the following three conditions must be met: 1) the defect is executed, 2) the program has transitioned into an infectious state, and 3) the infection has propagated to the output. Coincidental correctness arises when the program produces the correct output, while conditions 1) and 2) are met but not 3). In previous work, we showed that coincidental correctness is prevalent and demonstrated that it is a safety reducing factor for coverage-based fault localization. This work aims at cleansing test suites from coincidental correctness to enhance fault localization. Specifically, given a test suite in which each test has been classified as failing or passing, we present three variations of a technique that identify the subset of passing tests that are likely to be coincidentally correct. We evaluated the effectiveness of our techniques by empirically quantifying the following: 1) how accurately did they identify the coincidentally correct tests, 2) how much did they improve the effectiveness of coverage-based fault localization, and 3) how much did coverage decrease as a result of applying them. Using our better performing technique and configuration, the safety and precision of fault-localization was improved for 88% and 61% of the programs, respectively.