Symbolic Execution for Software Testing: Three Decades Later Cristian Cadar Koushik Sen Imperial College London University of California, Berkeley
[email protected] [email protected] Abstract A key goal of symbolic execution in the context of soft- Recent years have witnessed a surge of interest in symbolic ware testing is to explore as many different program paths execution for software testing, due to its ability to generate as possible in a given amount of time, and for each path to high-coverage test suites and find deep errors in complex (1) generate a set of concrete input values exercising that software applications. In this article, we give an overview path, and (2) check for the presence of various kinds of errors of modern symbolic execution techniques, discuss their key including assertion violations, uncaught exceptions, security challenges in terms of path exploration, constraint solving, vulnerabilities, and memory corruption. The ability to gener- and memory modeling, and discuss several solutions drawn ate concrete test inputs is one of the major strengths of sym- primarily from the authors’ own work. bolic execution: from a test generation perspective, it allows the creation of high-coverage test suites, while from a bug- Categories and Subject Descriptors D.2.5 [Testing and finding perspective, it provides developers with a concrete Debugging]: Symbolic execution input that triggers the bug, which can be used to confirm and debug the error independently of the symbolic execution tool General Terms Reliability that generated it. Furthermore, note that in terms of finding errors on a 1. Introduction given program path, symbolic execution is more powerful Symbolic execution has gathered a lot of attention in re- than traditional dynamic execution techniques such as those cent years as an effective technique for generating high- implemented by popular tools like Valgrind or Purify, which coverage test suites and for finding deep errors in com- depend on the availability of concrete inputs triggering the plex software applications.