Clarification about Jest?

[leo-petrucci]

I've read the testing docs page, but it seems seriously lacking any info.

My setup is the same, I have jest installed in my root package.json. However every time I try to run jest I get:

command not found: jest

Where should I install Jest? Can I have some shared Jest config in its own package? Do I need to install Jest in each workspace within my monorepo? (installint it in the workspace makes it work but then it requires me to manage Jest for each workspace which isn't great)

If I move install jest in the specific workspace I'm getting a lot of:

Cannot find name 'expect'.

What should the type setup be?

[anthonyshew]

We now have a dedicated Jest page. Sorry for not having it sooner!
https://turbo.build/repo/docs/guides/tools/jest

[tgdn]

Assuming most of my packages will have tests, does it make more sense setting up jest in the root and using projects [array<string | ProjectConfig>] as described in this SO answer?

[anthonyshew]

No, because then you can't cache tests per-package. Any time you make any change in the repository, you would miss cache for all tasks.