XSTRESSOR : Automatic Generation of Large-Scale Worst-Case Test Inputs by Inferring Path Conditions

An important part of software testing is generation of worst-case test inputs, which exercise a program under extreme loads. For such a task, symbolic execution is a useful tool with its capability to reason about all possible execution paths of a program, including the one with the worst case behavior. However, symbolic execution suffers from the path explosion problem and frequent calls to a constraint solver, which make it impractical to be used at a large scale. To address the issue, this paper presents XSTRESSOR that is able to generate test inputs that can run specific loops in a program with the worst-case complexity in a large scale. XSTRESSOR synthetically generates the path condition for the large-scale, worst-case execution from a predictive model that is built from a set of small scale tests. XSTRESSOR avoids the scaling problem of prior techniques by limiting full-blown symbolic execution and run-time calls to constraint solver to small scale tests only. We evaluate XSTRESSOR against WISE and SPF-WCA, the most closely related tools to generate worst-case test inputs. Results show that XSTRESSOR can generate the test inputs faster than WISE and SPF-WCA, and also scale to much larger input sizes.