4))
        .expect(1, 1, 2, 3);
  }

  public void testFlatMapToLong_nullStream() {
    SpliteratorTester.ofLong(
            () ->
                CollectSpliterators.flatMapToLong(
                    Arrays.spliterator(new Long[] {1L, 0L, 1L, 2L, 3L}),
                    (Long i) -> i == 0L ? null : LongStream.of(i).spliterator(),