Fix `AutoModelTest.test_model_from_pretrained` (#20730)

Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>

tests/models/auto/test_modeling_auto.py

@@ -22,7 +22,7 @@ from pathlib import Path
 
 import pytest
 
-from transformers import BertConfig, GPT2Model, is_torch_available
+from transformers import BertConfig, GPT2Model, is_safetensors_available, is_torch_available
 from transformers.models.auto.configuration_auto import CONFIG_MAPPING
 from transformers.testing_utils import (
     DUMMY_UNKNOWN_IDENTIFIER,
@@ -102,7 +102,10 @@ class AutoModelTest(unittest.TestCase):
             self.assertIsInstance(model, BertModel)
 
             self.assertEqual(len(loading_info["missing_keys"]), 0)
-            self.assertEqual(len(loading_info["unexpected_keys"]), 8)
+            # When using PyTorch checkpoint, the expected value is `8`. With `safetensors` checkpoint (if it is
+            # installed), the expected value becomes `7`.
+            EXPECTED_NUM_OF_UNEXPECTED_KEYS = 7 if is_safetensors_available() else 8
+            self.assertEqual(len(loading_info["unexpected_keys"]), EXPECTED_NUM_OF_UNEXPECTED_KEYS)
             self.assertEqual(len(loading_info["mismatched_keys"]), 0)
             self.assertEqual(len(loading_info["error_msgs"]), 0)