I don't think these tests are correctly testing the added part. The plugin search logic always starts from Prettier cli, if we want test, we'll have to put Prettier into those dirs. I don't know how to do that.

I could be misunderstanding the code, but I think in run-prettier.js the cwd gets set properly in run(). Either way, if I log autoLoadDir, it is set to the expected directory, so it does seem prettier is starting from the right directory.

Shouldn't plugins also stored like prettier-plugin-foo@1.0.0? I don't know how the @*/plugin-* stored, but are you sure these patterns correct?

In the pnpm virtual store, the three possible types of plugins (@prettier/plugin-*, and @<name>/prettier-plugin-*, prettier-plugin-*) are stored like this:

.pnpm/
├── @prettier+plugin-foo@<version>/
│   └── node_modules/
│       └── @prettier/
│           └── plugin-foo/
├── @<name>+prettier-plugin-bar@<version>/
│   └── node_modules/
│       └── @<name>/
│           └── prettier-plugin-bar/
└── prettier-plugin-baz@<version>/
    └── node_modules/
        └── prettier-plugin-baz/

I don't think the +package-name part of the directory used to be there, but now that it is, I can just have the patterns be ["prettier-plugin-*", "@prettier+plugin-*", "@*+prettier-plugin-*"].