@Test
  public void testSmallReversedScan02() throws IOException {
    Put put = new Put(new byte[] { (char) 0x00 });
    put.addColumn(COLUMN_FAMILY, null, Bytes.toBytes(0));
    htable.put(put);

    Scan scan = new Scan();
    scan.setCaching(1);
    scan.setReversed(true);
    scan.setReadType(ReadType.PREAD);

    ResultScanner scanner = htable.getScanner(scan);
    Result r;
    int count = 1;
    while ((r = scanner.next()) != null) {
      Assert.assertArrayEquals(r.getValue(COLUMN_FAMILY, null), Bytes.toBytes(0));
      Assert.assertArrayEquals(r.getRow(), new byte[] { (char) 0x00 });
      Assert.assertTrue(--count >= 0);
    }
    Assert.assertEquals(0, count);
  }
Corner case:
<p/>
HBase has 4 regions, (-oo,b),[b,c),[c,d),[d,+oo), and only rowKey with byte[]={0x00} locate in
region (-oo,b) . test whether reversed pread scanner will return infinity results with
RowKey={0x00}.
hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestPreadReversedScanner.java