caucase.test: Fix tarfile deprecation warning

caucase/test.py

@@ -84,6 +84,18 @@ from caucase.storage import SQLite3Storage
 
 _cryptography_backend = default_backend()
 
+if hasattr(tarfile, 'data_filter'): # pragma: no cover
+  # Silence a deprecation warning on Python 3.12
+  class TarFile(tarfile.TarFile):
+    """
+    tarball.TarFile with the future default filter.
+
+    Used to silence a deprecation warning.
+    """
+    extraction_filter = staticmethod(tarfile.data_filter)
+else: # pragma: no cover
+  TarFile = tarfile.TarFile
+
 def _getTestOID():
   """
   Some cryptography versions do not tolerate large OIDs. Detect these here.
@@ -463,14 +475,14 @@ class CaucaseTest(TestCase):
       self._startServer(timeout=60)
       self._stopServer()
       server_raw = BytesIO()
-      with tarfile.TarFile(mode='w', fileobj=server_raw) as server_tarball:
+      with TarFile(mode='w', fileobj=server_raw) as server_tarball:
         server_tarball.add(
           self._server_dir,
           arcname=os.path.basename(self._server_dir),
         )
       _clean_caucased_snapshot = server_raw.getvalue()
     else:
-      with tarfile.TarFile(
+      with TarFile(
         mode='r',
         fileobj=BytesIO(_clean_caucased_snapshot),
       ) as server_tarball: