### Question:
BatchingIterator implements Iterator<O> { @Override public boolean hasNext() { advance(); return output.hasNext(); } BatchingIterator(Iterator<I> input, Function<List<I>, Iterator<O>> nextBatch); @Override boolean hasNext(); @Override O next();  }### Answer:
@Test public void testInitializeWithoutIterator() { Iterator<Object> iterator = new BatchingIterator<>(null, nextBatch); assertFalse(iterator.hasNext()); }