@Test
  public void testMaxString() throws HiveException {
    testAggregateString(
        "max",
        2,
        Arrays.asList(new Object[]{"A","B","C"}),
        "C");
    testAggregateString(
        "max",
        2,
        Arrays.asList(new Object[]{"C", "B", "A"}),
        "C");
  }
Unit test for the vectorized GROUP BY operator.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorGroupByOperator.java