### Question:
EbftBlockKeyStore implements BlockKeyStore<Long, byte[]> { @Override public byte[] get(Long key) { if (key < 0) { log.debug("Key is not vaild."); return null; } lock.lock(); try { log.trace("get " + "({})", key); return db.get(ByteUtil.longToBytes(key)); } catch (Exception e) { log.debug(e.getMessage()); return null; } finally { lock.unlock(); } } EbftBlockKeyStore(DbSource<byte[], byte[]> dbSource); @Override void put(Long key, byte[] value); @Override byte[] get(Long key); @Override boolean contains(Long key); @Override long size(); @Override void close();  }### Answer:
@Test public void getTest_NegativeNumber() { assertNull(blockKeyStore.get(-1L)); }