match missing-shard test on the shard filename

huggingface_hub>=1.22.0 reports a missing cached shard via
IncompleteSnapshotError (repo-relative path) before diffusers' own
cached-folder check (absolute path) runs, so assert on the shard's
filename, which both messages contain.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: sayakpaul

tests/models/test_modeling_common.py

@@ -161,9 +161,11 @@ def test_local_files_only_with_sharded_checkpoint(self):
                     repo_id, subfolder="transformer", cache_dir=tmpdir, local_files_only=True
                 )
 
-            # Verify error mentions the missing shard
+            # Verify error mentions the missing shard. `huggingface_hub>=1.22.0` reports it via
+            # `IncompleteSnapshotError` (repo-relative path), older versions via diffusers' own check on the
+            # cached folder (absolute path), so match on the shard's filename.
             error_msg = str(context.value)
-            assert cached_shard_file in error_msg or "required according to the checkpoint index" in error_msg, (
+            assert os.path.basename(cached_shard_file) in error_msg, (
                 f"Expected error about missing shard, got: {error_msg}"
             )