@Override
    public String toString() {
        return getClass().getSimpleName() + " barCount: " + barCount;
    }
@Test
    public void onlyNaNValues() {
        BarSeries series = new BaseBarSeriesBuilder().withNumTypeOf(numFunction).withName("NaN test").build();
        for (long i = 0; i <= 1000; i++) {
            series.addBar(ZonedDateTime.now().plusDays(i), NaN, NaN, NaN, NaN, NaN);
        }

        AroonDownIndicator aroonDownIndicator = new AroonDownIndicator(series, 5);
        for (int i = series.getBeginIndex(); i <= series.getEndIndex(); i++) {
            assertEquals(NaN.toString(), aroonDownIndicator.getValue(i).toString());
        }
    }