withIndex.close();

    assertThat(doubleStreamCloseCount.get()).isEqualTo(1);
  }

  public void testZip() {
    assertThat(Streams.zip(Stream.of("a", "b", "c"), Stream.of(1, 2, 3), (a, b) -> a + ":" + b))
        .containsExactly("a:1", "b:2", "c:3")
        .inOrder();
  }

  public void testZip_closeIsPropagated() {
    AtomicInteger lettersCloseCount = new AtomicInteger();