Raise on evaluating a H-selector if specified player name is not valid in the game

src/pygambit/hsel.pxi

@@ -300,7 +300,19 @@ def _node_last_action(node: c_GameNode, player: str) -> object:
     """The label of the last action `player` took on the path to `node`
     (a raw handle, not a `Node`), wherever it fell -- `None` if `player`
     hasn't acted yet. The `c_GameNode`-only core of `_last_action`, used
-    directly by `HistoryView`, which must never hold a `Node`."""
+    directly by `HistoryView`, which must never hold a `Node`.
+
+    Raises
+    ------
+    KeyError
+        If no player in the game has label `player`.
+    TypeError
+        If `player` is not a `str`.
+    ValueError
+        If `player` is an empty string or all spaces.
+    """
+    game: Game = Game._wrap(node.deref().GetGame())
+    game._resolve_player(player, "last_action")
     current: c_GameNode = node
     parent: c_GameNode = current.deref().GetParent()
     while parent != cython.cast(c_GameNode, NULL):
@@ -373,7 +385,17 @@ class HistoryView:
 
     def last_action(self, player: str) -> str | None:
         """The label of the last action `player` took on the path to this
-        history, wherever it fell -- `None` if `player` hasn't acted yet."""
+        history, wherever it fell -- `None` if `player` hasn't acted yet.
+
+        Raises
+        ------
+        KeyError
+            If no player in the game has label `player`.
+        TypeError
+            If `player` is not a `str`.
+        ValueError
+            If `player` is an empty string or all spaces.
+        """
         return _node_last_action(self._node, player)
 
     @property

tests/test_hsel.py

@@ -117,3 +117,63 @@ def test_get_histories_requires_selector():
         game.get_histories(())
     with pytest.raises(TypeError):
         game.get_histories("U")
+
+
+def test_last_action_raises_on_invalid_player():
+    game = gbt.ExtensiveGame(players=["A", "B"])
+    game.append_move(gbt.H.path(), "A", ["U", "D"])
+    game.append_move(gbt.H.plays, "B", ["x", "y"])
+
+    def key(h):
+        with pytest.raises(KeyError):
+            h.last_action("NoSuchPlayer")
+        return None
+
+    game._get_groups(gbt.H.plays.by(key))
+
+
+def test_last_action_raises_on_non_str_player():
+    game = gbt.ExtensiveGame(players=["A"])
+    game.append_move(gbt.H.path(), "A", ["U", "D"])
+
+    def key(h):
+        with pytest.raises(TypeError):
+            h.last_action(1)
+        return None
+
+    game._get_groups(gbt.H.plays.by(key))
+
+
+def test_last_action_raises_on_empty_player():
+    game = gbt.ExtensiveGame(players=["A"])
+    game.append_move(gbt.H.path(), "A", ["U", "D"])
+
+    def key(h):
+        with pytest.raises(ValueError):
+            h.last_action("  ")
+        return None
+
+    game._get_groups(gbt.H.plays.by(key))
+
+
+def test_with_recall_raises_on_invalid_player():
+    game = gbt.ExtensiveGame(players=["A", "B"])
+    game.append_move(gbt.H.path(), "A", ["U", "D"])
+    game.append_move(gbt.H.plays, "B", ["x", "y"])
+
+    grouped = gbt.H.path().by(lambda h: None).with_recall("NoSuchPlayer").plays
+    with pytest.raises(KeyError):
+        game._get_groups(grouped)
+
+
+def test_with_recall_refines_key_by_last_action():
+    game = gbt.ExtensiveGame(players=["A", "B"])
+    game.append_move(gbt.H.path(), "A", ["U", "D"])
+    game.append_move(gbt.H.plays, "B", ["x", "y"])
+
+    grouped = gbt.H.path().by(lambda h: None).with_recall("A").plays
+    groups = game._get_groups(grouped)
+    assert {k: [h.actions for h in v] for k, v in groups.items()} == {
+        (None, "U"): [("U", "x"), ("U", "y")],
+        (None, "D"): [("D", "x"), ("D", "y")],
+    }