Hello @patak-js , @antfu , congrats great work around jest, it's refreshing.
I tried to integrate vitest inside our browser testing implementation, I had some issues 😦 Here is some issues I had during my integration:

• I think the run is too tied to fs and others node-only stuff. I like the idea of the runner and suites, but for being able to use only the runner it requires a lot of alias inside our build and mocking.
• by default the lib has narrow exports and it's blocking (at least me :)) to use internal stuff like collectFiles and runFiles, I managed to remove them locally but won't work by default.
• To me the DefaultReporter should not be part of the run module because it's linked to a lot to node environement.
• I wish I could hook/replace the snapshotManager 😍 (via config) like the reporter but I need different access to files than the node fs layer. And I think the exposed api could have been just matchSnapshot, toSnapshot, saveSnapshot, or something like this. I don't have a clear idea yet. Because for now I cannot use it to publish/save somewhere a snapshot
• I think also in the TaskResult api it lacks a duration or maybe it's me and I couldn't find it. As a suggestion I liked also what mocha did on timing by defining acceptable running timing (fast/medium/slow) being able to categorize them but for sure could be done with the reporter api.
  https://imgur.com/a/jex9gTJ
  and here is the snippet of code I use now for being able to run vitest in the browser https://gist.github.com/gqio/404001da5333d86f408e79ba19e33c8f

Sorry for the reporter not being very neat but at least it adapts my actual front report api and the vitest runner api 🙂
FTR I commented in the run module those lines to avoid bundling issue on my side

// import fg from 'fast-glob';
// import { setupChai } from '../integrations/chai/setup';
// import { DefaultReporter } from '../reporters/default';
// import { getSnapshotManager } from '../integrations/chai/snapshot';

Maybe splitting core feature and runtime could fit the need.

Wdyt ?