@Test
  public void testCountStar() throws HiveException {
    testAggregateCountStar(
        2,
        Arrays.asList(new Long[]{13L,null,7L,19L}),
        4L);
  }
Unit test for the vectorized GROUP BY operator.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorGroupByOperator.java