Change function argument defaults to immutable type

Co-authored-by: Matthias Büchse <[email protected]>
Signed-off-by: Markus Hentsch <[email protected]>

Author: markus-hentsch

Tests/iaas/volume-backup/volume-backup-tester.py

@@ -190,7 +190,7 @@ def cleanup(conn: openstack.connection.Connection, prefix=DEFAULT_PREFIX,
     """
 
     def wait_for_resource(resource_type: str, resource_id: str,
-                          expected_status=["available"]) -> None:
+                          expected_status=("available", )) -> None:
         seconds_waited = 0
         get_func = getattr(conn.block_storage, f"get_{resource_type}")
         while get_func(resource_id).status not in expected_status:
@@ -212,7 +212,7 @@ def wait_for_resource(resource_type: str, resource_id: str,
     for backup in backups:
         if backup.name.startswith(prefix):
             try:
-                wait_for_resource("backup", backup.id, ["available", "error"])
+                wait_for_resource("backup", backup.id, expected_status=("available", "error"))
             except openstack.exceptions.ResourceNotFound:
                 # if the resource has vanished on
                 # its own in the meantime ignore it
@@ -247,7 +247,7 @@ def wait_for_resource(resource_type: str, resource_id: str,
     for volume in volumes:
         if volume.name.startswith(prefix):
             try:
-                wait_for_resource("volume", volume.id, ["available", "error"])
+                wait_for_resource("volume", volume.id, expected_status=("available", "error"))
             except openstack.exceptions.ResourceNotFound:
                 # if the resource has vanished on
                 # its own in the meantime ignore it