@Test
  public void testSumDoubleGroupByString() throws HiveException {
    testAggregateDoubleStringKeyAggregate(
        "sum",
        4,
        Arrays.asList(new Object[]{"A", null, "A", null}),
        Arrays.asList(new Object[]{13.0,5.0,7.0,19.0}),
        buildHashMap("A", 20.0, null, 24.0));
  }
Unit test for the vectorized GROUP BY operator.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorGroupByOperator.java