assertThatDoubleStream(stream(OptionalDouble.of(5.0))).containsExactly(5.0);
  }

  public void testConcatInfiniteStream() {
    assertThat(Streams.concat(Stream.of(1, 2, 3), Stream.generate(() -> 5)).limit(5))
        .containsExactly(1, 2, 3, 5, 5)
        .inOrder();
  }

  public void testConcatInfiniteStream_int() {
    assertThat(Streams.concat(IntStream.of(1, 2, 3), IntStream.generate(() -> 5)).limit(5))