Use vitest to make unittest

[CoolPlayLin]

Currently, create-vue's testing script only includes test.mjs. I'd like this project to use vitest to test functions

[cexbrayat]

Yes, I think it could be handy as well 👍
If you feel like opening a PR, we'll gladly review it.

[CoolPlayLin]

I'd like to open PR. It would take a while

[CoolPlayLin]

Oh no, I cannot install vitest via pnpm