A family of code coverage-based heuristics for effective fault localization

W. Eric Wong, Vidroha Debroy, Byoungju Choi

Research output: Contribution to journalArticlepeer-review

199 Scopus citations


Locating faults in a program can be very time-consuming and arduous, and therefore, there is an increased demand for automated techniques that can assist in the fault localization process. In this paper a code coverage-based method with a family of heuristics is proposed in order to prioritize suspicious code according to its likelihood of containing program bugs. Highly suspicious code (i.e., code that is more likely to contain a bug) should be examined before code that is relatively less suspicious; and in this manner programmers can identify and repair faulty code more efficiently and effectively. We also address two important issues: first, how can each additional failed test case aid in locating program faults; and second, how can each additional successful test case help in locating program faults. We propose that with respect to a piece of code, the contribution of the first failed test case that executes it in computing its likelihood of containing a bug is larger than or equal to that of the second failed test case that executes it, which in turn is larger than or equal to that of the third failed test case that executes it, and so on. This principle is also applied to the contribution provided by successful test cases that execute the piece of code. A tool, χDebug, was implemented to automate the computation of the suspiciousness of the code and the subsequent prioritization of suspicious code for locating program faults. To validate our method case studies were performed on six sets of programs: Siemens suite, Unix suite, space, grep, gzip, and make. Data collected from the studies are supportive of the above claim and also suggest Heuristics III(a), (b) and (c) of our method can effectively reduce the effort spent on fault localization.

Original languageEnglish
Pages (from-to)188-208
Number of pages21
JournalJournal of Systems and Software
Issue number2
StatePublished - Feb 2010

Bibliographical note

Funding Information:
W. Eric Wong received his M.S. and Ph.D. in Computer Science from Purdue University, West Lafayette, Indiana. He is currently an associate professor in the Department of Computer Science at the University of Texas at Dallas. Dr. Wong is a recipient of the Quality Assurance Special Achievement Award from Johnson Space Center, NASA (1997). Prior to joining UT-Dallas, he was with Telcordia Technologies (formerly Bell Communications Research a.k.a. Bellcore) as a Senior Research Scientist and as the project manager in charge of the initiative for Dependable Telecom Software Development. Dr. Wong’s research focus is on the technology to help practitioners produce high quality software at low cost. In particular, he is doing research in the areas of software testing, debugging, safety, reliability, and metrics. He has received funding from such organizations as NSF, NASA, Avaya Research, Texas Instruments, and EDS/HP among others. He has published over 120 refereed papers in journals and conference/workshop proceedings. Dr. Wong has served as special issue guest editor for six journals and as general or program chair for many international conferences. He also serves as the Secretary of ACM SIGAPP and is on the Administrative Committee of the IEEE Reliability Society.


  • Code coverage
  • Failed tests
  • Fault localization
  • Heuristics
  • Program debugging
  • Successful tests
  • Suspiciousness of code


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