// Verify
    Iterator<Integer> iterator = iterable.iterator();
    assertFalse(iterator.hasNext());
    assertThrows(NoSuchElementException.class, () -> iterator.next());
  }

  public void testMergeSorted_single_empty() {
    // Setup
    Iterable<Integer> iterable0 = ImmutableList.of();
    Iterable<Iterable<Integer>> iterables = ImmutableList.of(iterable0);

    // Test & Verify