Cache Optimizations for Test Case Reduction

Finding the relevant part of failure-inducing inputs is an important first step on the path of debugging. If much of a test case that triggers a bug does not contribute to the actual failure, then the time required to fix the bug can increase considerably. In this paper, we focus on the memory requirements of automatic test case reduction. During minimization, the same test case might be tested multiple times, and determining the outcome of an input may take time, therefore, different caching solutions were proposed to avoid re-testing previously seen inputs. We investigated the caching solutions of DDMIN and HDD, and found that their scaling is suboptimal. We propose three optimizations for one of the state-of-the-art caching solutions: with the optimizations combined, DDMIN requires 96% and HDD requires 85% less memory compared to the baseline implementation. Furthermore, as a side effect, the reduction becomes faster by 9.9% with DDMIN.