@Test
  public void testMinLongNullStringKeys() throws HiveException {
    testAggregateStringKeyAggregate(
        "min",
        2,
        Arrays.asList(new Object[]{"A",null,"A",null}),
        Arrays.asList(new Object[]{13L, 5L, 7L,19L}),
        buildHashMap("A", 7L, null, 5L));
  }
Unit test for the vectorized GROUP BY operator.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorGroupByOperator.java