@Test
  public void testSetKey() {
    TimeSeries s1 = new TimeSeries("S");
    s1.setKey("S1");
    assertEquals("S1", s1.getKey());

    TimeSeriesCollection c = new TimeSeriesCollection();
    c.addSeries(s1);
    TimeSeries s2 = new TimeSeries("S2");
    c.addSeries(s2);

    // now we should be allowed to change s1's key to anything but "S2"
    s1.setKey("OK");
    assertEquals("OK", s1.getKey());

    try {
      s1.setKey("S2");
      fail("Expect an exception here.");
    } catch (IllegalArgumentException e) {
      // OK
    }

    // after s1 is removed from the collection, we should be able to set
    // the key to anything we want...
    c.removeSeries(s1);
    s1.setKey("S2");

    // check that removing by index also works
    s1.setKey("S1");
    c.addSeries(s1);
    c.removeSeries(1);
    s1.setKey("S2");
  }
  /** Check that cloning works. */
  @Test
  public void testClone() throws CloneNotSupportedException {

    TimeSeries series = new TimeSeries("Test Series");
    RegularTimePeriod jan1st2002 = new Day(1, MonthConstants.JANUARY, 2002);
    series.add(jan1st2002, new Integer(42));

    TimeSeries clone;
    clone = (TimeSeries) series.clone();
    clone.setKey("Clone Series");
    clone.update(jan1st2002, new Integer(10));

    int seriesValue = series.getValue(jan1st2002).intValue();
    int cloneValue = clone.getValue(jan1st2002).intValue();

    assertEquals(42, seriesValue);
    assertEquals(10, cloneValue);
    assertEquals("Test Series", series.getKey());
    assertEquals("Clone Series", clone.getKey());
  }