private static DateFormat format = new SimpleDateFormat("yyyy-MM-dd");
@Test
public void afterDate() {
String source = "2011-04-07";
Calendar value = new DateTimeFunction(toCalendar(source, format), DateType.AFTER).generateValue();
assertNotNull("Generated date can not be null", value);
assertTrue(String.format("Generated date is not after %s", source), value.after(toCalendar(source, format)));
}