@Test
  public void testVarLongNullKeyGroupBySingleBatch() throws HiveException {
    testAggregateLongKeyAggregate(
        "variance",
        4,
        Arrays.asList(new Long[]{null,2L,01L,02L,01L,01L}),
        Arrays.asList(new Long[]{13L, 5L,18L,19L,12L,15L}),
        buildHashMap(null, 0.0, 2L, 49.0, 01L, 6.0));
  }
Unit test for the vectorized GROUP BY operator.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorGroupByOperator.java