gulp: gulp 5 seems to break existing streaming plugins

What were you expecting to happen?

After upgrading from gulp 4.x to gulp 5, I was expecting my built-in plugin to “streamify” async functions so they can be put in the gulp pipeline without having to write bespoke plugins for everything to work as before.

What actually happened?

Tests around streamify hang. Breaking into the code, I see that the original transform creation is called, the transform is passed back, and the body of the transform is never executed.

Please give us a sample of your gulpfile

See example at https://github.com/fluffynuts/gulp-streamify - streamify.spec.ts has the calls to gulp, so you can npm test to see the failures.

Whilst I’ve pulled this out into its own repo to make it easier to use to repro the issue, this plugin is not published, and may never be, as it’s consumed internally on another project.

I’ve included the original function as-is, using through2, and an “updated” one based on the docs at https://github.com/gulpjs/gulp/tree/master/docs/writing-a-plugin - both don’t work.

Please provide the following information:

• OS & version: Windows 11 23h2 (22631.3155)
• node version (run node -v): 18.18.2
• npm version (run npm -v): 9.8.1
• gulp version (run gulp -v): 5.0.0