### Question:
HBaseClient10 extends com.yahoo.ycsb.DB { @Override public Status scan(String table, String startkey, int recordcount, Set<String> fields, Vector<HashMap<String, ByteIterator>> result) { if (!tableName.equals(table)) { currentTable = null; try { getHTable(table); tableName = table; } catch (IOException e) { System.err.println("Error accessing HBase table: " + e); return Status.ERROR; } } Scan s = new Scan(Bytes.toBytes(startkey)); s.setCaching(recordcount); if (this.usePageFilter) { s.setFilter(new PageFilter(recordcount)); } if (fields == null) { s.addFamily(columnFamilyBytes); } else { for (String field : fields) { s.addColumn(columnFamilyBytes, Bytes.toBytes(field)); } } ResultScanner scanner = null; try { scanner = currentTable.getScanner(s); int numResults = 0; for (Result rr = scanner.next(); rr != null; rr = scanner.next()) { String key = Bytes.toString(rr.getRow()); if (debug) { System.out.println("Got scan result for key: " + key); } HashMap<String, ByteIterator> rowResult = new HashMap<String, ByteIterator>(); while (rr.advance()) { final Cell cell = rr.current(); rowResult.put(Bytes.toString(CellUtil.cloneQualifier(cell)), new ByteArrayByteIterator(CellUtil.cloneValue(cell))); } result.add(rowResult); numResults++; if (numResults >= recordcount) { break; } } } catch (IOException e) { if (debug) { System.out.println("Error in getting/parsing scan result: " + e); } return Status.ERROR; } finally { if (scanner != null) { scanner.close(); } } return Status.OK; }  @Override void init(); @Override void cleanup(); void getHTable(String table); Status read(String table, String key, Set<String> fields,
      HashMap<String, ByteIterator> result); @Override Status scan(String table, String startkey, int recordcount,
      Set<String> fields, Vector<HashMap<String, ByteIterator>> result); @Override Status update(String table, String key,
      HashMap<String, ByteIterator> values); @Override Status insert(String table, String key,
      HashMap<String, ByteIterator> values); @Override Status delete(String table, String key);  }### Answer:
@Test public void testScan() throws Exception { final String colStr = "row_number"; final byte[] col = Bytes.toBytes(colStr); final int n = 10; final List<Put> puts = new ArrayList<Put>(n); for(int i = 0; i < n; i++) { final byte[] key = Bytes.toBytes(String.format("%05d", i)); final byte[] value = java.nio.ByteBuffer.allocate(4).putInt(i).array(); final Put p = new Put(key); p.addColumn(Bytes.toBytes(COLUMN_FAMILY), col, value); puts.add(p); } table.put(puts); final Vector<HashMap<String, ByteIterator>> result = new Vector<HashMap<String, ByteIterator>>(); client.scan(CoreWorkload.table, "00001", 5, null, result); assertEquals(5, result.size()); for(int i = 0; i < 5; i++) { final HashMap<String, ByteIterator> row = result.get(i); assertEquals(1, row.size()); assertTrue(row.containsKey(colStr)); final byte[] bytes = row.get(colStr).toArray(); final ByteBuffer buf = ByteBuffer.wrap(bytes); final int rowNum = buf.getInt(); assertEquals(i + 1, rowNum); } }