add CommandResult.NeedsAction

app/src/main/java/chess/io/commands/MoveCommand.java

@@ -3,6 +3,7 @@ package chess.io.commands;
 import chess.io.OutputSystem;
 import chess.io.PlayerCommand;
 import chess.model.ChessBoard;
+import chess.model.Coordinate;
 import chess.model.Game;
 import chess.model.Move;
 import chess.model.Piece;
@@ -49,6 +50,9 @@ public class MoveCommand extends PlayerCommand {
 			return CommandResult.NotAllowed;
 		}
 
+		if (shouldPromote(game, outputSystem)) 
+			return CommandResult.ActionNeeded;
+
 		return CommandResult.Moved;
 	}
 
@@ -59,4 +63,14 @@ public class MoveCommand extends PlayerCommand {
 		board.undoMove(move, deadPiece);
 	}
 
+	private boolean shouldPromote(Game game, OutputSystem outputSystem) {
+		Coordinate pawnPos = game.pawnPromotePosition();
+
+		if (pawnPos == null)
+			return false;
+
+		outputSystem.promotePawn(pawnPos);
+		return true;
+	}
+
 }