@Test
public void testTwoBufferingSpliteratorsConsumedInParallel() {

    SeqBuffer<Integer> buffer = buffer();
    List<Tuple2<Integer, Integer>> expected = Seq.zip(list, list).toList();
    // calls 1 & 2: two buffering spliterators and parallel consumption of both
    List<Tuple2<Integer, Integer>> actual = Seq.zip(buffer.seq(), buffer.seq()).toList();
    assertEquals(expected, actual);
    assertEquals(list, buffer.seq().toList()); // call 3: buffered spliterator + complete consumption
}