the case i had, when i ran the unit test, i got the error message: To use Server Actions, please enable the feature flag in your Next.js config. Read more: https://nextjs.org/docs/app/building-your-application/data-fetching/server-actions#convention.
I myself have previously tried enabling Server Actions, and testing the function that I created, the function's purpose is to create a User, and send it to the database.