promote gui

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

@@ -24,6 +24,10 @@ public class MoveCommand extends Command {
 	public CommandResult execute(Game game, OutputSystem outputSystem) {
 		final ChessBoard board = game.getBoard();
 
+		// we must promote the pending pawn before
+		if (game.pawnShouldBePromoted())
+			return CommandResult.NotAllowed;
+
 		Piece piece = board.pieceAt(move.getStart());
 		if (piece == null)
 			return CommandResult.NotAllowed;

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

@@ -49,7 +49,7 @@ public class PromoteCommand extends Command {
 		board.pieceLeaves(this.pieceCoords);
 		board.pieceComes(createPiece(this.promoteType, pawn.getColor()), this.pieceCoords);
 
-		return CommandResult.NotMoved;
+		return CommandResult.Moved;
 	}
 
 	private Piece createPiece(PromoteType promoteType, Color color) {