public void testGetRowAndColumnCount() {
        double[] starts_S1 = new double[] {0.1, 0.2, 0.3};
        double[] starts_S2 = new double[] {0.3, 0.4, 0.5};
        double[] ends_S1 = new double[] {0.5, 0.6, 0.7};
        double[] ends_S2 = new double[] {0.7, 0.8, 0.9};
        double[][] starts = new double[][] {starts_S1, starts_S2};
        double[][] ends = new double[][] {ends_S1, ends_S2};
        DefaultIntervalCategoryDataset d 
                = new DefaultIntervalCategoryDataset(starts, ends);        

        assertEquals(2, d.getRowCount());
        assertEquals(3, d.getColumnCount());