### Question:
ClientBuffer { public void destroy() { List<SerializedPageReference> removedPages; PendingRead pendingRead; synchronized (this) { removedPages = ImmutableList.copyOf(pages); pages.clear(); bufferedBytes.getAndSet(0); noMorePages = true; destroyed.set(true); pendingRead = this.pendingRead; this.pendingRead = null; } removedPages.forEach(SerializedPageReference::dereferencePage); if (pendingRead != null) { pendingRead.completeResultFutureWithEmpty(); } } ClientBuffer(String taskInstanceId, OutputBufferId bufferId); BufferInfo getInfo(); boolean isDestroyed(); void destroy(); void enqueuePages(Collection<SerializedPageReference> pages); ListenableFuture<BufferResult> getPages(long sequenceId, DataSize maxSize); ListenableFuture<BufferResult> getPages(long sequenceId, DataSize maxSize, Optional<PagesSupplier> pagesSupplier); void setNoMorePages(); void loadPagesIfNecessary(PagesSupplier pagesSupplier); void acknowledgePages(long sequenceId); @Override String toString();  }### Answer:
@Test public void testAddAfterDestroy() { ClientBuffer buffer = new ClientBuffer(TASK_INSTANCE_ID, BUFFER_ID); buffer.destroy(); addPage(buffer, createPage(0)); addPage(buffer, createPage(0)); assertBufferDestroyed(buffer, 0); }
@Test public void testDestroy() { ClientBuffer buffer = new ClientBuffer(TASK_INSTANCE_ID, BUFFER_ID); for (int i = 0; i < 5; i++) { addPage(buffer, createPage(i)); } buffer.setNoMorePages(); assertBufferResultEquals(TYPES, getBufferResult(buffer, 0, sizeOfPages(1), NO_WAIT), bufferResult(0, createPage(0))); buffer.destroy(); assertBufferDestroyed(buffer, 0); assertBufferResultEquals(TYPES, getBufferResult(buffer, 1, sizeOfPages(1), NO_WAIT), emptyResults(TASK_INSTANCE_ID, 0, true)); }
@Test public void testReferenceCount() { ClientBuffer buffer = new ClientBuffer(TASK_INSTANCE_ID, BUFFER_ID); AtomicBoolean page0HasReference = addPage(buffer, createPage(0)); AtomicBoolean page1HasReference = addPage(buffer, createPage(1)); assertTrue(page0HasReference.get()); assertTrue(page1HasReference.get()); assertBufferInfo(buffer, 2, 0); assertBufferResultEquals(TYPES, getBufferResult(buffer, 0, sizeOfPages(0), NO_WAIT), bufferResult(0, createPage(0))); assertTrue(page0HasReference.get()); assertTrue(page1HasReference.get()); assertBufferInfo(buffer, 2, 0); assertBufferResultEquals(TYPES, getBufferResult(buffer, 1, sizeOfPages(1), NO_WAIT), bufferResult(1, createPage(1))); assertFalse(page0HasReference.get()); assertTrue(page1HasReference.get()); assertBufferInfo(buffer, 1, 1); buffer.destroy(); assertFalse(page0HasReference.get()); assertFalse(page1HasReference.get()); assertBufferDestroyed(buffer, 1); }