### Question:
PbftBlockKeyStore implements BlockKeyStore<Long, byte[]> { @Override public void close() { lock.lock(); try { this.db.close(); } finally { lock.unlock(); } } PbftBlockKeyStore(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 closeTest() { blockKeyStore.close(); TestCase.assertNull(blockKeyStore.get(this.pbftBlock0.getIndex())); this.blockKeyStore = new PbftBlockKeyStore(ds); byte[] newHash = blockKeyStore.get(0L); assertArrayEquals(this.pbftBlock0.getHash().getBytes(), newHash); }