Yes, as a major version bump, Vitest v4 introduces several breaking changes you'll need to handle when migrating from v3.
You can find the full details in the official Vitest v4 Migration Guide.
Here are some of the most significant breaking changes to be aware of:
- Pool Options: The
poolOptionsconfiguration is gone. Options likethreadsorvmare now set at the top level of yourtestconfig. - Workers:
maxThreadsandmaxForkshave been consolidated into a single option:maxWorkers.