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馃敡 chore(test): add opt-in Atheris fuzz harness - #3246
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OpenSSF Scorecard's Fuzzing check scores 0 with no signal in the repo that any fuzzing happens. Rather than add a token import just to move the number, this fuzzes two real hand-rolled escaping implementations: NushellActivator.quote (a `#`-run-counting raw-string scheme) and PowerShellActivator.quote (single-quote doubling). Both take arbitrary strings from paths and prompts, and a broken escape is a real correctness bug, not just a lint target. Each harness recomputes the expected output from the escaping rule independently and asserts equality, so it catches actual scheme violations, not just crashes. Verified the assertions against both targets with 200k+ randomized adversarial strings before wiring them into atheris, since atheris itself can't build here (Apple Clang ships without libFuzzer). Atheris only ships Linux wheels for CPython 3.12-3.14, so it lives in its own "fuzz" dependency group, installed nowhere else, with a marker that skips it entirely outside that combination instead of triggering a doomed source build. tox -e fuzz is opt-in and not part of env_list, so nothing changes for any other environment or CI job.
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OpenSSF Scorecard's Fuzzing check scores 0 for this repo. Its detection only checks for
import atheris(or a ClusterFuzzLite/OSS-Fuzz setup) anywhere in the tree, so this adds a real target rather than a token import that would move the number without doing anything.NushellActivator.quoteandPowerShellActivator.quoteare hand-rolled escaping schemes over arbitrary strings pulled from paths and prompts: Nushell counts the longest run of#and wraps in one more than that, PowerShell doubles single quotes. Both take untrusted-shaped input, and a broken escape is a correctness bug worth catching, not just a lint target. Each harness intasks/fuzz_*.pyrecomputes the expected output from the escaping rule on its own and asserts equality against the real function, so it fails on any scheme violation, not only on a crash. I ran both assertions against 200k+ randomized adversarial strings (embedded quotes,#runs, control characters, Unicode) against the real functions before wiring them into Atheris.Atheris only ships prebuilt wheels for Linux + CPython 3.12-3.14 - it doesn't build on this machine at all, since Apple Clang doesn't ship libFuzzer. It lives in its own
fuzzdependency group with a marker matching that exact combination, so nothing else ever tries to install it or falls into a doomed source build.tox -e fuzzis opt-in and outsideenv_list, so no existing environment or CI job changes.