clan-cli/tests: improve test helpers for VMs

pkgs/clan-cli/tests/helpers/nixos_config.py

@@ -0,0 +1,11 @@
+from collections import defaultdict
+from collections.abc import Callable
+from typing import Any
+
+
+def def_value() -> defaultdict:
+    return defaultdict(def_value)
+
+
+# allows defining nested dictionary in a single line
+nested_dict: Callable[[], dict[str, Any]] = lambda: defaultdict(def_value)