@Test
  public void getLower() throws Exception {

    String lower = support.getSysPeriodLower("t0", "sys_period");
    assertEquals(lower, "t0.sys_period_start");
  }
  @Test
  public void getUpper() throws Exception {

    String upper = support.getSysPeriodUpper("t0", "sys_period");
    assertEquals(upper, "t0.sys_period_end");
  }
  @Test
  public void getAsOfPredicate() {

    String asOfPredicate = support.getAsOfPredicate("t0", "sys_period");
    assertEquals(asOfPredicate, "(t0.sys_period_start <= ? and (t0.sys_period_end is null or t0.sys_period_end > ?))");
  }