FutureMoves: add (failing) test for situation encountered during testing

src/logic/future_moves.rs

@@ -637,4 +637,49 @@ mod tests {
             vec![(0, vec![0, 2]), (1, vec![1]), (2, vec![3])]
         );
     }
+
+    #[test]
+    fn best_move_failure() {
+        let mut futm = FutureMoves::new(Piece::Black, FUTURE_MOVES_CONFIG);
+        let mut board = Board::new().starting_pos();
+
+        // replay of a test I did
+        // TODO! make this as small of a test as possible
+        let moves = vec![
+            (Some((5, 4)), Piece::Black),
+            (Some((5, 5)), Piece::White),
+            (Some((5, 6)), Piece::Black),
+            (Some((6, 4)), Piece::White),
+            (Some((7, 3)), Piece::Black),
+            (Some((7, 4)), Piece::White),
+            (Some((7, 5)), Piece::Black),
+            (Some((2, 4)), Piece::White),
+            (Some((1, 4)), Piece::Black),
+            (Some((1, 5)), Piece::White),
+            (Some((1, 6)), Piece::Black),
+            (Some((0, 6)), Piece::White),
+            (Some((3, 2)), Piece::Black),
+            (Some((1, 7)), Piece::White),
+            (None, Piece::Black), // black skips a move
+            (Some((0, 4)), Piece::White),
+            (None, Piece::Black), // black skips a move
+            (Some((4, 2)), Piece::White),
+        ];
+
+        for (coords, color) in moves {
+            if color == futm.agent_color {
+                // my turn
+                futm.update_from_board(&board);
+                let best_move = futm.best_move();
+                if coords.is_none() {
+                    assert_eq!(best_move, None);
+                } else {
+                    assert_ne!(best_move, None);
+                }
+            }
+            if let Some((i, j)) = coords {
+                board.place(i, j, color).unwrap();
+            }
+        }
+    }
 }