Module-level getattr breaks unittest functionality

[chschroeder]

System Info

Certain functions from the unittest package are broken if transformers is loaded:

ModuleNotFoundError: No module named 'torchvision'

For me, the error occurs because torchvision is not installed. The error, however, is a more systematic one. From the stack trace, I ended up here:

transformers/src/transformers/__init__.py

Lines 854 to 871 in 856157a

	def getattr_factory(target):
	def _getattr(name):
	if name.endswith("Fast"):
	new_name = name.removesuffix("Fast")
	logger.warning_once(
	"Accessing `%s` from `%s`. Returning `%s` instead. Behavior may be "
	"different and this alias will be removed in future versions.",
	name,
	target,
	new_name,
	)
	return getattr(importlib.import_module(target, __name__), new_name)
	# Silently forward non-Fast names to target (transparent alias behavior)
	return getattr(importlib.import_module(target, __name__), name)
	return _getattr
	sys.modules[f"{__name__}.models.{_model}.{_module}_fast"].__getattr__ = getattr_factory(_target)

This later interferes with unittest. See here for the example of assertWarnsRegex():

https://github.com/python/cpython/blob/c016c2535b74227fddf2cf7334dbfead6c930214/Lib/unittest/case.py#L289-L298

---

Environment:
Python 3.12
transformers 5.17.0
torchvision not installed

**Full stacktrace**

  Traceback (most recent call last):
  File "", line 16, in 
  File "", line 10, in test
  File "/user/.pyenv/versions/3.12.8/lib/python3.12/unittest/case.py", line 293, in __enter__
    if getattr(v, '__warningregistry__', None):
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/user/workspaces/small-text/.nox/8e14c2bf/lib/python3.12/site-packages/transformers/__init__.py", line 867, in _getattr
    return getattr(importlib.import_module(target, __name__), name)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/user/.pyenv/versions/3.12.8/lib/python3.12/importlib/__init__.py", line 90, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "", line 1387, in _gcd_import
  File "", line 1360, in _find_and_load
  File "", line 1331, in _find_and_load_unlocked
  File "", line 935, in _load_unlocked
  File "", line 999, in exec_module
  File "", line 488, in _call_with_frames_removed
  File "/user/workspaces/small-text/.nox/8e14c2bf/lib/python3.12/site-packages/transformers/models/aria/image_processing_aria.py", line 23, in 
    from torchvision.transforms.v2 import functional as tvF

Who can help?

No response

Information

• The official example scripts
• My own modified scripts

Tasks

• An officially supported task in the examples folder (such as GLUE/SQuAD, ...)
• My own task or dataset (give details below)

Reproduction

import unittest
import transformers  # uncomment to fix the reported error


class TestWarning(unittest.TestCase):
    def test_warns_regex(self):
        with self.assertWarnsRegex(DeprecationWarning, r"hello"):
            pass


if __name__ == "__main__":
    unittest.main()

Expected behavior

The test should output: AssertionError: DeprecationWarning not triggered (or respectively pass with a different testing logic, but it should not fail with an unrelated import).