Guard the object store test helper module for isolated package testing

pytest collects _unification_utils.py directly, so its module-level galaxy.files
imports must also be guarded with importorskip (not just the test modules that use
them). Fixes the remaining "Test Galaxy packages" collection error.

Author: nuwang

test/unit/objectstore/_unification_utils.py

@@ -6,10 +6,18 @@
 import os
 from uuid import uuid4
 
-from galaxy.files.plugins import FileSourcePluginsConfig
-from galaxy.files.unittest_utils import TestConfiguredFileSources
+import pytest
+
 from galaxy.util import directory_hash_id
 
+# These helpers need galaxy-files + fsspec; skip cleanly when the galaxy-objectstore package
+# is tested in isolation without them (this module is collected directly by pytest).
+pytest.importorskip("fsspec")
+pytest.importorskip("galaxy.files")
+
+from galaxy.files.plugins import FileSourcePluginsConfig  # noqa: E402  (after importorskip)
+from galaxy.files.unittest_utils import TestConfiguredFileSources  # noqa: E402  (after importorskip)
+
 
 class Dataset:
     def __init__(self, id):