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voicebox/backend/tests/test_offline_patch.py
T
Jamie PineandGitHub d61e884104 fix(offline): patch transformers mistral-regex check to survive HF failures (#530)
* fix(offline): patch transformers mistral-regex check to survive HF failures

transformers 4.57.x's `PreTrainedTokenizerBase._patch_mistral_regex` calls
`huggingface_hub.model_info(repo_id)` unconditionally during any non-local
tokenizer load to probe for Mistral-family models. The call raises on
`HF_HUB_OFFLINE=1`, on network outages, and on slow/blocked HF endpoints,
and transformers doesn't catch any of it — the exception bubbles out of
`from_pretrained` and kills the load for unrelated engines (Qwen TTS,
Qwen CustomVoice, TADA, etc.).

0.4.2's load-time `force_offline_if_cached` guard walked straight into
this trap: on cached online users it flipped `HF_HUB_OFFLINE=1` and
converted a healthy load into a hard crash. 0.4.3's inference-path guard
masked it; #524 removed the inference guard in 0.4.4, and users updating
to 0.4.4 started hitting the same error on the load path instead
(#526).

Fix:
- Wrap `_patch_mistral_regex` so any exception from the inner HF
  metadata check is swallowed and the tokenizer is returned unchanged.
  Voicebox never loads Mistral models, so the regex rewrite this check
  gates is a no-op for us; matches the success-path behavior for
  non-Mistral repos (tokenization_utils_base.py:2503).
- Drop the `force_offline_if_cached` wraps from every load path
  (pytorch_backend Qwen + Whisper, qwen_custom_voice_backend,
  mlx_backend Qwen + Whisper). With the mistral patch in place they
  provide zero value and only risk re-introducing the same class of
  bug. Helper and its unit tests stay — still correct for targeted
  future use.
- Add `backend/tests/test_offline_patch.py` covering
  OfflineModeIsEnabled / ConnectionError suppression, success
  pass-through, idempotence, and the missing-method no-op path.

Fixes #526.

* fix(offline): install mistral-regex patch for non-MLX backends

The previous commit left the patch wired only through ``mlx_backend.py``'s
existing import of ``hf_offline_patch``. On Windows/Linux/CUDA users who
never load the MLX backend (everyone who hit #526), the patch module was
never imported, so ``patch_transformers_mistral_regex`` never ran and the
crash persisted.

Hoist the import into ``backends/__init__.py``. Every backend imports from
this package, so the module-level patch install runs before any
``from_pretrained`` call regardless of which engine the user picks.

Caught by CodeRabbit and Cursor Bugbot on #530.
2026-04-21 22:01:29 -07:00

114 lines
3.4 KiB
Python

"""
Unit tests for ``patch_transformers_mistral_regex``.
Verifies that our wrapper around
``transformers.PreTrainedTokenizerBase._patch_mistral_regex`` catches
exceptions from the unconditional ``huggingface_hub.model_info()`` lookup
and returns the tokenizer unchanged — matching the success-path behavior
for non-Mistral repos (transformers 4.57.3, ``tokenization_utils_base.py:2503``).
NOTE: These tests mutate ``transformers.PreTrainedTokenizerBase`` globally;
run serially, not under ``pytest-xdist`` with per-worker process isolation.
"""
import sys
from pathlib import Path
import pytest
sys.path.insert(0, str(Path(__file__).parent.parent))
from huggingface_hub.errors import OfflineModeIsEnabled # noqa: E402
from transformers.tokenization_utils_base import PreTrainedTokenizerBase # noqa: E402
import utils.hf_offline_patch as hf_offline_patch # noqa: E402
@pytest.fixture(autouse=True)
def restore_mistral_regex():
"""Snapshot the current ``_patch_mistral_regex`` and restore after each test."""
saved = PreTrainedTokenizerBase.__dict__.get("_patch_mistral_regex")
saved_flag = hf_offline_patch._mistral_regex_patched
try:
yield
finally:
if saved is not None:
PreTrainedTokenizerBase._patch_mistral_regex = saved
hf_offline_patch._mistral_regex_patched = saved_flag
def _apply_patch():
hf_offline_patch._mistral_regex_patched = False
hf_offline_patch.patch_transformers_mistral_regex()
def test_suppresses_offline_mode_is_enabled(monkeypatch):
_apply_patch()
import huggingface_hub
def raise_offline(*_args, **_kwargs):
raise OfflineModeIsEnabled("offline")
monkeypatch.setattr(huggingface_hub, "model_info", raise_offline)
sentinel = object()
result = PreTrainedTokenizerBase._patch_mistral_regex(
sentinel, "Qwen/Qwen3-TTS-12Hz-1.7B-Base"
)
assert result is sentinel
def test_suppresses_connection_errors(monkeypatch):
_apply_patch()
import huggingface_hub
def raise_connection(*_args, **_kwargs):
raise ConnectionError("network unreachable")
monkeypatch.setattr(huggingface_hub, "model_info", raise_connection)
sentinel = object()
result = PreTrainedTokenizerBase._patch_mistral_regex(
sentinel, "Qwen/Qwen3-TTS-12Hz-1.7B-Base"
)
assert result is sentinel
def test_passthrough_on_success(monkeypatch):
"""When model_info returns non-Mistral tags the original falls through and returns the tokenizer unchanged."""
_apply_patch()
import huggingface_hub
class FakeInfo:
tags = ["model-type:qwen", "language:en"]
monkeypatch.setattr(huggingface_hub, "model_info", lambda *_a, **_kw: FakeInfo())
sentinel = object()
result = PreTrainedTokenizerBase._patch_mistral_regex(
sentinel, "Qwen/Qwen3-TTS-12Hz-1.7B-Base"
)
assert result is sentinel
def test_idempotent():
_apply_patch()
first = PreTrainedTokenizerBase._patch_mistral_regex
hf_offline_patch.patch_transformers_mistral_regex()
second = PreTrainedTokenizerBase._patch_mistral_regex
assert first.__func__ is second.__func__
def test_missing_method_is_noop(monkeypatch):
monkeypatch.delattr(PreTrainedTokenizerBase, "_patch_mistral_regex", raising=False)
hf_offline_patch._mistral_regex_patched = False
hf_offline_patch.patch_transformers_mistral_regex()
assert hf_offline_patch._mistral_regex_patched is False
if __name__ == "__main__":
pytest.main([__file__, "-v"])