public void testConstructor1() {
        YIntervalDataItem item1 = new YIntervalDataItem(1.0, 2.0, 3.0, 4.0);
        assertEquals(new Double(1.0), item1.getX());
        assertEquals(2.0, item1.getYValue(), EPSILON);
        assertEquals(3.0, item1.getYLowValue(), EPSILON);
        assertEquals(4.0, item1.getYHighValue(), EPSILON);