@Before
  public void setup() throws Exception {
    tn = TableName.valueOf("test-" + util.getRandomUUID());
    args = new HashMap<>();
    // Prepare the arguments required for the test.
    args.put(ImportTsv.COLUMNS_CONF_KEY, "HBASE_ROW_KEY,FAM:A,FAM:B");
    args.put(ImportTsv.SEPARATOR_CONF_KEY, "\u001b");
  }
Force use of combiner in doMROnTableTest. Boolean. Default is true.
hbase-mapreduce/src/test/java/org/apache/hadoop/hbase/mapreduce/TestImportTsv.java