Fix sys.modules leak in offline cross-sync test (#926)

reload_zoo popped unsloth_zoo from sys.modules and re-imported it without
restoring the original module. The reimport installs a fresh package object
that lacks lazily-bound submodule attributes such as vision_utils, so once
this fixture had run, any later test resolving a submodule through a string
path (monkeypatch.setattr("unsloth_zoo.vision_utils....", ...)) failed with
AttributeError. This surfaced as 5 errors in test_vision_collator_audio.py in
full-suite runs while every test passed in isolation.

Snapshot the unsloth_zoo* modules and restore them on teardown so the reload
no longer leaks a half-initialized package into the rest of the session.

Also patch the imported module object directly in the audio collator test
instead of the string path, so it stays robust to any future sys.modules
pollution.

Author: danielhanchen

tests/test_offline_env_cross_sync.py

@@ -24,15 +24,38 @@
 @pytest.fixture
 def reload_zoo(monkeypatch):
     """Strip the three offline env vars, then reload ``unsloth_zoo`` so its
-    import-time cross-sync runs."""
+    import-time cross-sync runs.
+
+    Reloading swaps a fresh, half-initialized ``unsloth_zoo`` object into
+    ``sys.modules`` -- one that lacks submodule attributes (e.g.
+    ``vision_utils``) the package only binds when they are first imported.
+    Snapshot the original ``unsloth_zoo*`` modules and restore them on
+    teardown so the reload does not leak that shell into the rest of the
+    session and break later tests that resolve submodules via string paths
+    (e.g. ``monkeypatch.setattr("unsloth_zoo.vision_utils.<attr>", ...)``).
+    """
     for v in ("HF_HUB_OFFLINE", "TRANSFORMERS_OFFLINE", "HF_DATASETS_OFFLINE"):
         monkeypatch.delenv(v, raising = False)
 
+    saved = {
+        name: module
+        for name, module in sys.modules.items()
+        if name == "unsloth_zoo" or name.startswith("unsloth_zoo.")
+    }
+
     def _reload():
         sys.modules.pop("unsloth_zoo", None)
         return importlib.import_module("unsloth_zoo")
 
-    return _reload
+    yield _reload
+
+    for name in [
+        name for name in sys.modules
+        if name == "unsloth_zoo" or name.startswith("unsloth_zoo.")
+    ]:
+        if name not in saved:
+            del sys.modules[name]
+    sys.modules.update(saved)
 
 
 class TestOfflineCrossSync:

tests/test_vision_collator_audio.py

@@ -507,8 +507,14 @@ def __getitem__(self, key):
 @pytest.fixture
 def _recognize_unpatched_decoder(monkeypatch):
     # Treat _UnpatchedFakeAudioDecoder as the decoder type so these run in CI.
+    # Patch the imported module object directly rather than the
+    # "unsloth_zoo.vision_utils._audio_decoder_types" string path: the string
+    # form resolves unsloth_zoo through sys.modules at runtime, so a preceding
+    # test that swaps unsloth_zoo in sys.modules would break resolution here.
+    import unsloth_zoo.vision_utils as vision_utils
     monkeypatch.setattr(
-        "unsloth_zoo.vision_utils._audio_decoder_types",
+        vision_utils,
+        "_audio_decoder_types",
         lambda: (_UnpatchedFakeAudioDecoder,),
     )