@Override
    public Num calculate(Position position, int currentIndex) {
        return this.calculate(position);
    }
@Test
    public void calculateOpenSellPosition() {
        // Calculate the transaction costs of an open position
        int currentIndex = 4;
        Position position = new Position(Trade.TradeType.BUY, transactionModel, new ZeroCostModel());
        position.operate(0, DoubleNum.valueOf(100), DoubleNum.valueOf(1));

        Num costsFromModel = transactionModel.calculate(position, currentIndex);

        assertNumEquals(costsFromModel, DoubleNum.valueOf(1));
    }