How should I implement proper plugin discovery that is pnpm proof?

[nicojs]

I'm the maintainer of StrykerJS, which has a plugin autodiscovery feature similar to Karma's. It isn't pnpm compatible. How should plugin discovery actually work? Let me explain.

A karma plugins-style tool works like this:

• karma is the core package; it doesn't have its plugin as a dependency (neither as a direct dependency nor a peer dependency).
• karma-jasmine is a plugin; it lists karma in its peer dependencies.
• karma requires karma-jasmine, because it automatically requires packages matching karma-*.

There are two problems here:

1. The auto-discovery works by walking the file system. This won't work with pnpm because the files are in different locations (and symlinked).
2. When karma uses require('karma-jasmine'), it effectively imports a dependency that isn't listed in its package.json, meaning that this probably shouldn't work.

Solving the first issue might be as simple as listing all known karma plugins and trying them out one by one. However, the second issue is more complicated to solve. What should karma do in this case? Should it import from cwd? For example, require.resolve('karma-jasmine', { paths: [process.cwd()] })? And how would that work with ESM, since we don't have an easy way to 'import from cwd'? Or is there some other way to make this work?