@BeforeClass
  public static void setUpBeforeClass() throws Exception {
    // switch TIF to log at DEBUG level
    Log4jUtils.enableDebug(MultiTableInputFormatBase.class);
    // start mini hbase cluster
    TEST_UTIL.startMiniCluster(3);
    // create and fill table
    for (String tableName : TABLES) {
      try (Table table =
        TEST_UTIL.createMultiRegionTable(TableName.valueOf(tableName), INPUT_FAMILY, 4)) {
        TEST_UTIL.loadTable(table, INPUT_FAMILY, false);
      }
    }
  }
Base set of tests and setup for input formats touching multiple tables.
hbase-mapreduce/src/test/java/org/apache/hadoop/hbase/mapreduce/MultiTableInputFormatTestBase.java