chore: migrate to mocha and eslint 9

[43081j]

Migrates from Jest to mocha and node's own assert library.

Also updates ESLint to 9.x and bumps TSESLint to do the same.

@fb55 what do you think of this? jest is pretty hefty for what we need, this trims a fair chunk of the dependency weight out. mocha, tinyspy and node assert seem pretty clean together to me

similarly, I dropped most eslint customisation we had and just opted to rely on the recommended configs since prettier should pick up all the stylistic stuff we care about

[43081j]

typescript started to complain without this, since you must have module: "node16" if you have module resolution set to it (which we do)

I guess it got updated in the lockfile while updating tseslint etc and introduced the new behaviour

[fb55]

Nice!

Could we use Node's own test runner and skip having any dependencies?

[43081j]

we could but I wasn't sure what node version matrix we wanted

the node test runner is available in 16.x onwards if I remember correctly

I'm also not sure off the top of my head how you get it to run typescript (via ts-node still presumably)

[43081j]

maybe lets go with mocha for now and I can try the node runner in a separate PR? since I feel like it'll be a bit more work

[wooorm]

I’d love all this stuff, but separate PRs makes reviewing this easier!

[43081j]

there's basically two changes (mocha and eslint). I could open two separate PRs but it gets a bit weird since I need to setup eslint to be happy with jest, knowing it'll go away immediately after

it may turn out its as easy as globals.jest but I'll have to try it out to find out

if you're unhappy with it going ahead without me splitting it up though I can have a look

[wooorm]

Right, sure. There are ways around that, with things like // todo(@43081j): remove this workaround when using builtin node test or so. I particularly said this because @fb55 suggested to use node:test instead of mocha anyway.

I’m not going to block this. But in my experience splitting PRs up into different things helps.

[43081j]

yes, I think we should go ahead with mocha first though anyway since the node test runner will be more work

I'll see if I can split into two PRs

it wouldn't be a TODO for removing a workaround for node:test, it'd be temporary lint config to make ESLint happy about jest globals and what not. we'd then remove that in the mocha PR

[43081j]

Closing in favour of #1268 and #1267