@Test
  public void testMapPlan1() throws Exception {

    LOG.info("Beginning testMapPlan1");
    populateMapPlan1(db.getTable(Warehouse.DEFAULT_DATABASE_NAME, "src"));
    executePlan();
    fileDiff("lt100.txt.deflate", "mapplan1.out");
  }
test reduce with multiple tagged inputs.
ql/src/test/org/apache/hadoop/hive/ql/exec/TestExecDriver.java