Validate n_iterations in MCTS

Author: direkkakkar319-ops

pyaptamer/mcts/_algorithm.py

@@ -74,6 +74,9 @@ def __init__(
         n_iterations: int = 1000,
         experiment=None,
     ) -> None:
+        if n_iterations < 1:
+            raise ValueError(f"`n_iterations` must be >= 1, got {n_iterations}.")
+
         self.experiment = experiment
         self.depth = depth
         self.n_iterations = n_iterations

pyaptamer/mcts/tests/test_mcts.py

@@ -241,6 +241,12 @@ def mcts(request):
 class TestMCTS:
     """Tests for the MCTS() class."""
 
+    @pytest.mark.parametrize("n_iterations", [0, -1])
+    def test_init_invalid_iterations(self, n_iterations):
+        """Check invalid iteration counts are rejected early."""
+        with pytest.raises(ValueError, match=r"`n_iterations` must be >= 1"):
+            MCTS(n_iterations=n_iterations)
+
     def test_reset(self, mcts):
         """Check correct reset of the inner state."""
         # modify its inner state