@Test
  public void noDataRegionTest() {
    String[] expectedHeader =
        new String[] {count("root.test.noDataRegion.s1"), sum("root.test.noDataRegion.s1")};
    String[] retArray = new String[] {"0,null,"};
    resultSetEqualWithDescOrderTest(
        "select count(s1), sum(s1) from root.test.noDataRegion", expectedHeader, retArray);

    expectedHeader = new String[] {DEVICE, count("s1"), sum("s1")};
    retArray = new String[] {"root.test.noDataRegion,0,null,"};
    resultSetEqualTest(
        "select count(s1), sum(s1) from root.test.noDataRegion align by device",
        expectedHeader,
        retArray);
  }
test aggregation query with more than one functions on one series
integration-test/src/test/java/org/apache/iotdb/db/it/aggregation/IoTDBAggregationIT.java