There is a general expectation that composer test will also work for MediaWiki core, just like it does in every other repository. But because core is so big, CI has a special system for it so it doesn't lint everything on every patch. We should switch that to a different entrypoint, and then repurpose composer test for humans.
If I do:
$ composer lint
It doesn't work, as the command it does is parallel-lint --exclude vendor which doesn't specify what directory.
I tried adding a dot to the end, which didn't seem to work as it had lots of red x's. But it was progressing really slowly so I ended up killing the process before it finished