We switched from Jest to Vitest this summer as part of the effort to migrate a large node repository to ESM. Jest presented a lot of issues after switching to ESM. Vitest was compatible with our existing jest code, minus a couple altered method signatures. It was also compatible with custom matchers we had implemented with jest-extend.

Most of the migration effort was spent on configuration for our needs. Vitest is quite flexible so it was just a matter of nailing down what worked for us.