### Question:
DBBuffer { public void delete() throws IOException { synchronized (dbh) { dbh.checkTransaction(); buf.delete(); } } DBBuffer(DBHandle dbh, ChainedBuffer buf); DBBuffer split(int offset); void setSize(int size, boolean preserveData); int length(); int getId(); void fill(int startOffset, int endOffset, byte fillByte); void append(DBBuffer buffer); byte getByte(int offset); void get(int offset, byte[] data, int dataOffset, int length); void fill(InputStream in); void put(int offset, byte[] bytes, int dataOffset, int length); void put(int offset, byte[] bytes); void putByte(int offset, byte b); void get(int offset, byte[] data); void delete();  }### Answer:
@Test public void testDelete() throws IOException { DBBuffer buf = null; long txId = dbh.startTransaction(); try { buf = dbh.createBuffer(1000); } catch (NoTransactionException e) { fail("Unexpected check transaction failure"); } finally { dbh.endTransaction(txId, true); } int bufId = buf.getId(); try { buf.delete(); fail("Expected check transaction failure"); } catch (NoTransactionException e) { } txId = dbh.startTransaction(); try { buf.delete(); } catch (NoTransactionException e) { fail("Unexpected check transaction failure"); } finally { dbh.endTransaction(txId, true); } try { buf = dbh.getBuffer(bufId); fail("Expected invalid buffer error"); } catch (IOException e) { } dbh.undo(); buf = dbh.getBuffer(bufId); assertEquals("Expected valid buffer", 0, buf.getByte(0)); }