The _stream_wrap module is deprecated

On node 12.13.0 I see this warning:

(node:3822) [DEP0125] DeprecationWarning: The _stream_wrap module is deprecated.

It can be a low priority, of course, but it’s nice to keep track of it.

[pimterry]

Now fixed in Mockttp v2.5.0. The patch above is used to avoid the deprecation warning for all Node releases > v12. For v12 and older _stream_wrap is still required (the fix described here doesn’t work) but v12 is EOL in April so I’m fine with that.

I’ve also opened a PR to fix the underlying issue in Node itself in https://github.com/nodejs/node/pull/41185. That’s approved by a few Node maintainers now, but not yet merged. Hopefully that’ll make it in for Node v18 and potentially get backported as well, which will allow us to remove the patch here entirely, and should help a fair few other HTTP/2 use cases too.

[pimterry]

Yes, good to keep track of this.

Some context: this is used in https://github.com/httptoolkit/httpolyglot to ensure we can work around certain node issues. _stream_wrap exposes a wrapper class, that wraps a stream so you can use it as a net.Socket directly. E.g. so you can create a TLS connection on top of any duplex stream. When we set up connections, if they’re backed by such a wrapper rather than a raw net socket, then the servers avoid making certain (incorrect) assumptions about the raw socket buffers under the hood. We add wrappers for some HTTP/2 cases, to fix some assumptions made there.

I’ve been talking to the node team about this already, there’s further context in https://github.com/nodejs/node/issues/34296 if you’re interested. The conclusion is that we shouldn’t actually need _stream_wrap here, because every use case should actually be supported and working, so these are fundamentally just workarounds for node bugs, but right now those node bugs still exist, so it’s unfortunately hard to remove in the short term. That’s true for every currently supported node release, AFAIK, but hopefully there’ll be progress there soon! Once those issues disappear, we can remove this (at least, when using new node releases).

If the deprecation is a big problem in the meantime, we could do an inline require instead in httppolyglot, so that it only appears when the first HTTP/2 request appears. I’m inclined not to by default though, just to keep things simple, unless it does start to cause problems.