Abstract

The Apollo project at IBM Research aims to develop practical automated techniques for finding and localizing bugs in web applications. We adapted an existing dynamic test generation technique that combines concrete and symbolic execution to the domain of web applications written in PHP , and used it to find dozens of failures in open-source PHP applications. To help programmers with localizing the faults that cause these failures, we adapted existing fault localization techniques that predict in which statements a fault is located by applying a statistical analysis to execution data gathered from multiple tests. Our results indicate that, using our best technique, 87.7% of faults are localized to within 1% of all executed statements. We also address the question of how to localize a fault when the programmer is confronted with a failure but no test suite is available that can be used for fault localization. In such cases, our new directed test generation technique is capable of generating small test suites with high fault-localization effectiveness.

This research is joint work with Shay Artzi, Danny Dig, Julian Dolby, Michael Ernst, Adam Kiezun, and Marco Pistoia. More details about this work can be found in our ISSTA ’08, ICSE ’10, and ISSTA ’10 papers.

Frank Tip received his PhD in 1995 from the University of Amsterdam. Since then, he has been with IBM Research, where he is currently managing the Program Analysis and Transformation Group. Frank’s current research interests include Refactoring, Test Generation and Fault Localization for Web Applications, Data-Centric Synchronization and Declarative Object Identity for Object-Oriented Programming Languages, and Change Impact Analysis. Frank is currently on sabbatical with the Programming Tools Group at the University of Oxford.