@Test
public void testAdd() {

  SettableApiFuture<Void> future = SettableApiFuture.create();
  when(batcher.add(rowMutation)).thenReturn(future);
  ApiFuture<Void> result = bulkMutationClient.add(rowMutation);
  assertFalse(result.isDone());
  future.set(null);
  assertTrue(result.isDone());
  verify(batcher).add(rowMutation);
}