@Test
  public void testMROnTable() throws Exception {
    util.createTable(tn, FAMILY);
    doMROnTableTest(null, 1);
    util.deleteTable(tn);
  }
Force use of combiner in doMROnTableTest. Boolean. Default is true.
hbase-mapreduce/src/test/java/org/apache/hadoop/hbase/mapreduce/TestImportTsv.java