From f0a2087bdd5b1029f17eae9a2582320dcb9937c6 Mon Sep 17 00:00:00 2001
From: Josh <josh@joshuaschuett.com>
Date: Tue, 19 Aug 2025 15:48:40 -0400
Subject: [PATCH] Add some additional sanity checks for move gen

---
 test/test_legal_move_gen.py | 46 +++++++++++++++++++++++++++++++++----
 1 file changed, 42 insertions(+), 4 deletions(-)

diff --git a/test/test_legal_move_gen.py b/test/test_legal_move_gen.py
index b21c561..1cf1cbf 100644
--- a/test/test_legal_move_gen.py
+++ b/test/test_legal_move_gen.py
@@ -1,9 +1,11 @@
 from test.base import ChessLibTestBase
 from test.chess_ffi import Move
 from test.chess_ffi import Board
-from test.chess_ffi import sq_to_coord
+from test.chess_ffi import BLACK
+from test.chess_ffi import WHITE
+from test.chess_ffi import is_in_check
 from test.chess_ffi import gen_legal_moves
-
+from test.chess_ffi import sq
 
 MAX_MOVES = 256
 
@@ -60,9 +62,45 @@ class TestLegalMoveGen(ChessLibTestBase):
         self.assertEqual(n, 44)
 
     
-    def test_pert_position_6(self):
+    def test_perft_position_6(self):
         fen = "r4rk1/1pp1qppp/p1np1n2/2b1p1B1/2B1P1b1/P1NP1N2/1PP1QPPP/R4RK1 w - - 0 10"
         b = Board(); self.load_fen(fen, board=b)
 
         n, moves = self._gen_legal(b)
-        self.assertEqual(n, 46)
\ No newline at end of file
+        self.assertEqual(n, 46)
+
+
+    def test_stalemate_black_to_move(self):
+        # Classic stalemate: Black to move, no legal moves, not in check
+        fen = "7k/5Q2/6K1/8/8/8/8/8 b - - 0 1"
+        b = Board()
+        self.load_fen(fen, board=b)
+
+        moves = (Move * MAX_MOVES)()
+        n = gen_legal_moves(b, moves)
+
+        self.assertEqual(n, 0, "Stalemate should have 0 legal moves")
+        self.assertFalse(is_in_check(b, BLACK), "Side to move must not be in check in stalemate")
+    
+
+    def test_simple_checkmate(self):
+        # Black to move; mated (Qg7# with Kg6 support)
+        fen = "7k/6Q1/6K1/8/8/8/8/8 b - - 0 1"
+        b = Board(); self.load_fen(fen, board=b)
+        moves = (Move * MAX_MOVES)()
+        n = gen_legal_moves(b, moves)
+
+        self.assertEqual(n, 0, "Checkmated side should have 0 legal moves")
+        self.assertTrue(is_in_check(b, BLACK), "Mated side must be in check")
+
+
+    def test_pinned_piece_cannot_move(self):
+            # White knight e2 pinned by rook e8 vs king e1
+            fen = "4r3/8/8/8/8/8/4N3/4K3 w - - 0 1"
+            b = Board(); self.load_fen(fen, board=b)
+            moves = (Move * MAX_MOVES)()
+            n = gen_legal_moves(b, moves)
+
+            for move in moves:
+                # Pinned knight cannot move from it's square.
+                self.assertFalse(getattr(move, "from") == sq("e2"))
\ No newline at end of file