Add repetition detection

src/board/game.rs

@@ -244,6 +244,14 @@ impl Game {
             }
         }
     }
+
+    pub fn in_repetition(&self) -> bool {
+        if self.board.state.halfmove_clock < 4 {
+            return false;
+        }
+
+        self.history.in_repetition(self.hash)
+    }
 }
 
 impl Default for Game {
@@ -431,4 +439,23 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn test_in_repetition() -> Result<(), String> {
+        let mut game = from_fen(FEN)?;
+
+        game.make_move(&Move::new(Square::F3, Square::E3));
+        game.make_move(&Move::new(Square::F7, Square::G7));
+        game.make_move(&Move::new(Square::E3, Square::F3));
+        game.make_move(&Move::new(Square::G7, Square::F7));
+        game.make_move(&Move::new(Square::F3, Square::E3));
+
+        assert!(game.in_repetition());
+
+        game.make_move(&Move::new(Square::H7, Square::H6));
+
+        assert!(!game.in_repetition());
+
+        Ok(())
+    }
 }