public Result[] next(long scannerId, int numberOfRows) throws IOException {
    // Just return one result whatever they ask for.
    Result r = next(scannerId);
    return r == null ? null : new Result[] { r };
  }
Use this method to set what a scanner will reply as we next through
hbase-server/src/test/java/org/apache/hadoop/hbase/master/MockRegionServer.java