Change- and gap-directed testing
LLM-based testing is becoming effective when generation is anchored to a concrete execution target. DiffTestGen uses call graphs, documentation, and coverage feedback to reach modified Python code. Across 463 pull requests, it exposed behavioral differences in 78.2% and averaged 90.7% union coverage.
GapForge applies the same targeting logic to compiler coverage gaps. It infers the program structures and compiler options needed to reach uncovered regions. In 72-hour runs, it exceeded WhiteFox by 24,736 covered GCC lines and 19,798 LLVM lines, and found 12 compiler failures. These results strengthen the recent evidence for executable checks by showing that the location and structure of feedback matter, not merely the presence of a test loop.