### Question:
BulkMutationWrapper implements IBulkMutation { @Override public void flush() throws InterruptedException { delegate.flush(); } BulkMutationWrapper(BulkMutation bulkMutation); @Override ApiFuture<Void> add(RowMutationEntry rowMutation); @Override void sendUnsent(); @Override void flush(); @Override void close();  }### Answer:
@Test public void testFlush() throws InterruptedException { doNothing().when(mockDelegate).flush(); bulkWrapper.flush(); verify(mockDelegate).flush(); }