@Test
public void testToIso()
{

    assertEquals( new DateTimeUnit( 1993, 3, 21, true ),
        calendar.toIso( new DateTimeUnit( 1372, 1, 1 ) ) );
    assertEquals( new DateTimeUnit( 2020, 3, 20, true ),
        calendar.toIso( new DateTimeUnit( 1399, 1, 1 ) ) );
    assertEquals( new DateTimeUnit( 2020, 3, 20, true ),
        calendar.toIso( new DateTimeUnit( 2020, 3, 20 ) ) );
}