@Test
public void testAddMutate() {

  RowMutationEntry rowMutation = RowMutationEntry.create("key");
  MutateRowsRequest.Entry requestProto = rowMutation.toProto();
  when(mockDelegate.add(requestProto))
      .thenReturn(Futures.immediateFuture(MutateRowResponse.getDefaultInstance()));
  Future<Void> response = bulkWrapper.add(rowMutation);
  try {
    response.get();
  } catch (Exception ex) {
    throw new AssertionError("Assertion failed for BulkMutationWrapper#add(RowMutation)");
  }
  verify(mockDelegate).add(requestProto);
}