/** Some checks for the findRangeBounds() method. */
  public void testFindRangeBounds() {
    StackedBarRenderer r = new StackedBarRenderer();
    assertNull(r.findRangeBounds(null));

    // an empty dataset should return a null range
    DefaultCategoryDataset dataset = new DefaultCategoryDataset();
    assertNull(r.findRangeBounds(dataset));

    dataset.addValue(1.0, "R1", "C1");
    assertEquals(new Range(0.0, 1.0), r.findRangeBounds(dataset));

    dataset.addValue(-2.0, "R1", "C2");
    assertEquals(new Range(-2.0, 1.0), r.findRangeBounds(dataset));

    dataset.addValue(null, "R1", "C3");
    assertEquals(new Range(-2.0, 1.0), r.findRangeBounds(dataset));

    dataset.addValue(2.0, "R2", "C1");
    assertEquals(new Range(-2.0, 3.0), r.findRangeBounds(dataset));

    dataset.addValue(null, "R2", "C2");
    assertEquals(new Range(-2.0, 3.0), r.findRangeBounds(dataset));
  }