@Test
public void testIsAfter()
{

    Period april = periodType.createPeriod( new DateTime( 2009, 4, 1, 0, 0 ).toDate() );
    Period may = periodType.createPeriod( new DateTime( 2009, 5, 1, 0, 0 ).toDate() );
    
    assertTrue( may.isAfter( april ) );
    assertFalse( april.isAfter( may ) );
    assertFalse( may.isAfter( null ) );
}