* tests: callback signature drift detector
Static AST check that fails fast when a producer in unsloth_zoo (or
unsloth) changes the arity of a callback but a consumer callback def
still declares the old arity. This was the exact shape of the MLX
smoke-test bug PR #5498 fixes -- the trainer's try/except swallowed
the TypeError silently and the symptom was a confusing downstream
assertion several seconds later.
What the detector does:
* Producer side: walks every .py and finds classes that own a
self._<name>_callbacks list, populated via .append() from an
add_<name>_callback method, and invoked via
`for cb in self._<name>_callbacks: cb(arg1, ..., argN)`. The
arity at the call site is the canonical expected arity.
* Consumer side: walks every <obj>.add_<name>_callback(fn) call,
resolves fn to a def or lambda in the same file, and asserts
arity matches. Consumers that use *args or **kwargs are
tolerantly accepted as any arity.
* Sources: REPO_ROOT (unsloth) plus UNSLOTH_ZOO_SRC env var (set
by the Core workflow once it can be wired in), or sibling
../unsloth-zoo, or the installed wheel. Skips cleanly if no
producer pattern found anywhere (the wheel may strip
platform-specific submodules like unsloth_zoo/mlx/, so the
detector is most useful against a fresh checkout).
Validated end-to-end:
* Reverted run_real_mlx_smoke.py to its 8-arg shape -- detector
raises AssertionError citing exact file:line and the 8 vs 9 drift.
* Restored the 9-arg shape -- detector PASSes.
* Total runtime ~7 s in pytest.
Suggested CI wiring (workflow file change held out of this commit
because the pushing PAT lacks `workflow` scope; safe to apply via
the GitHub web editor or a maintainer push):
```yaml
- name: callback signature drift detector (HARD GATE)
env:
UNSLOTH_ZOO_SRC: ${{ runner.temp }}/unsloth-zoo
run: |
python -m pytest -v --tb=short tests/test_callback_signature_drift.py
```
Drop the step into .github/workflows/consolidated-tests-ci.yml right
after the existing public-api drift detector step. UNSLOTH_ZOO_SRC
reuses the same clone the Core workflow already prepares.
* [pre-commit.ci] auto fixes from pre-commit.com hooks
for more information, see https://pre-commit.ci
* ci: wire callback-signature drift detector into Core matrix
Drops a 6-line pytest step right after the public-api drift detector,
with UNSLOTH_ZOO_SRC pointed at the freshly cloned $RUNNER_TEMP/unsloth-zoo
so the detector sees unsloth_zoo/mlx/ (the wheel strips it).
Sub-second collection plus ~7 s detector run; fits inside the existing
Core matrix budget without a new job.
---------
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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