@Test
public void testUnion() {

nal DateTime t = new DateTime(2013, 12, 11, 8, 0, 0);
nal DateTime t2 = new DateTime(2013, 12, 11, 13, 0, 0);
    final SpanImpl newSpan = new SpanImpl(Period.ONE_HOUR, t, t2);
nal DateTime t3 = new DateTime(2013, 12, 11, 12, 0, 0);
nal DateTime t4 = new DateTime(2013, 12, 11, 16, 0, 0);
    final SpanImpl newSpan2 = new SpanImpl(Period.ONE_HOUR, t3, t4);
    final SpanImpl union = newSpan.union(newSpan2);
sertEquals(t, union.getDate());
sertEquals(t4, union.getNextDate());
}