@Test
public void testAddMutate() throws ExecutionException, InterruptedException {

  RowMutationEntry rowMutation = RowMutationEntry.create("key");
  MutateRowsRequest.Entry requestProto = rowMutation.toProto();
  when(mockDelegate.add(requestProto))
      .thenReturn(Futures.immediateFuture(MutateRowResponse.getDefaultInstance()));
  bulkMutationWrapper.add(rowMutation).get();
  verify(mockDelegate).add(requestProto);
}