coverage-analysis
An agent skill by trailofbits, from trailofbits/skills. Tags: analysis, cli, performance, testing.
What it does
Measures and interprets what a fuzzing campaign actually reaches, using llvm-cov, lcov, or a fuzzer's own coverage output. Covers baselining a new campaign, reading coverage reports, and turning uncovered regions into harness, seed, or dictionary work. Use when a fuzzer plateaus, when judging whether a harness is effective, after changing a harness, or when asking why some code is never reached.
Install
With the skills CLI, which installs into Claude Code, Codex, Cursor and other agents:
npx skills add trailofbits/skills --skill coverage-analysisOr copy the skill folder into Claude Code's skills directory by hand (~/.claude/skills for every project, or .claude/skills inside one):
git clone --depth 1 https://github.com/trailofbits/skills
cp -r skills/plugins/testing-handbook-skills/skills/coverage-analysis ~/.claude/skills/coverage-analysisSafety box score
Not rated yet. A safety box score grades what a skill and its scripts can reach on the machine of whoever installs it, across eight categories from shell execution to secrets access. Anyone can request one from this page; it is saved for everyone. How the score works.
Source
- Repository
- trailofbits/skills (all skills from this repository)
- Path
- plugins/testing-handbook-skills/skills/coverage-analysis/SKILL.md
- Branch
- main
- Collection
- testing-handbook-skills
- Updated
- 2026-09-19
Related skills
- seo-unlighthouse — Multi-page Lighthouse audit via the MIT-licensed Unlighthouse CLI.
- address-sanitizer — Builds and runs code under AddressSanitizer to catch buffer overflows, use-after-free, and other memory errors during fuzzing or tests.
- aflpp — Sets up and runs AFL++ for multi-core fuzzing of C/C++ projects built with afl-clang-fast or afl-gcc-fast.
- cargo-fuzz — Sets up and runs cargo-fuzz, the standard fuzzing tool for Cargo-based Rust projects. Covers cargo fuzz init, the nightly toolchain requirement, fuzz_target!
- constant-time-testing — Measures timing side channels in cryptographic implementations by running them.
- fuzzing-dictionary — Builds and applies fuzzing dictionaries so a fuzzer can produce the keywords, magic bytes, and tokens a target expects.