add test marker to run all tests with @require_bitsandbytes (#28278)

pyproject.toml

@@ -32,4 +32,5 @@ doctest_optionflags="NUMBER NORMALIZE_WHITESPACE ELLIPSIS"
 doctest_glob="**/*.md"
 markers = [
     "flash_attn_test: marks tests related to flash attention (deselect with '-m \"not flash_attn_test\"')",
+    "bitsandbytes: select (or deselect with `not`) bitsandbytes integration tests",
 ]

src/transformers/testing_utils.py

@@ -966,9 +966,17 @@ def require_aqlm(test_case):
 
 def require_bitsandbytes(test_case):
     """
-    Decorator for bits and bytes (bnb) dependency
+    Decorator marking a test that requires the bitsandbytes library. Will be skipped when the library or its hard dependency torch is not installed.
     """
-    return unittest.skipUnless(is_bitsandbytes_available(), "test requires bnb")(test_case)
+    if is_bitsandbytes_available() and is_torch_available():
+        try:
+            import pytest
+
+            return pytest.mark.bitsandbytes(test_case)
+        except ImportError:
+            return test_case
+    else:
+        return unittest.skip("test requires bitsandbytes and torch")(test_case)
 
 
 def require_optimum(test_case):