added (failing) perft, debugging required

tests/perft.rs

@@ -1,7 +1,37 @@
 use chess_engine::board::Board;
 use chess_engine::movegen::generate_pseudo_legal_moves;
+use chess_engine::movegen::legal_check::is_king_attacked;
 use chess_engine::r#move::MoveList;
 
+fn count_legal_moves_recursive(board: &mut Board, depth: u8) -> u64 {
+    if depth == 0 {
+        return 1_u64;
+    }
+
+    let mut list = MoveList::new();
+    generate_pseudo_legal_moves(&board, &mut list);
+
+    let mut leaf_nodes = 0_u64;
+    for mv in list.iter() {
+        // Store the undo info when making the move
+        let undo_info = board.make_move(*mv);
+
+        if !is_king_attacked(board) {
+            leaf_nodes += count_legal_moves_recursive(board, depth - 1);
+        }
+
+        // Undo the move to restore the board state for the next iteration
+        board.undo_move(undo_info);
+    }
+    leaf_nodes
+}
+
+#[test]
+fn perft() {
+    let mut board = Board::from_fen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");
+    println!("{}", count_legal_moves_recursive(&mut board, 4));
+}
+
 
 // "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1" 7 3195901860 "false"
 // "r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq -" 5 193690690 "false"