fixup! test_dir_traversal: Document the .add() calls set up in test v…

…ectors

tests/test_dir_traversal.py

@@ -2,7 +2,7 @@
 from abc import ABC, abstractmethod
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import Generic, List, NamedTuple, Optional, Tuple, TypeVar, Union
+from typing import Generic, List, Optional, Tuple, TypeVar, Union
 
 import pytest
 
@@ -89,14 +89,15 @@ def prepare(self, tmp_path: Path) -> TraversalStep:
         )
 
 
-class AddCall(NamedTuple, Generic[T]):
+@dataclass(frozen=True)
+class AddCall(Generic[T]):
     """Arguments for a call to DirectoryTraversal.add()."""
 
     path: Union[Path, str]
     attach: Tuple[T, ...] = ()
 
 
-@dataclass
+@dataclass(frozen=True)
 class DirectoryTraversalVector(Generic[T]):
     """Test vectors for DirectoryTraversal."""
 
@@ -267,8 +268,8 @@ def test_DirectoryTraversal(vector: DirectoryTraversalVector, tmp_path):
         entry(tmp_path)
 
     traversal: DirectoryTraversal = DirectoryTraversal()
-    for path, data_items in vector.add:
-        traversal.add(tmp_path / path, *data_items)
+    for call in vector.add:
+        traversal.add(tmp_path / call.path, *call.attach)
     for path in vector.skip_dirs:
         traversal.skip_dir(tmp_path / path)