Retrofitting exception handling from tests: static and dynamic analysis in context pushed pass@1 to 85.92% on 304 stripped methods

arXiv 2609.10397·medium signalXBlueskyLinkedInCopy link

EXCODER defines a new task, adding missing exception-related code (throw statements, their guard conditions, try/catch blocks) to existing code so that given exceptional behavior tests pass. It does context engineering, feeding LLMs extracted static and dynamic program analysis rather than the raw method. On a benchmark built by systematically removing exception code from 304 methods across 75 GitHub Java projects, EXCODER with Qwen 2.5 Coder 32b reached 85.92% pass@1, 12.56 percentage points over baseline, with similar margins at pass@5 and pass@10 on developer-written test suites. Manual inspection found real limitations, so the authors call it effective but imperfect.