feat: add unit test framework

[blva]

• adds jest as a testing framework

[gagik]

Don't have strong feelings about this but we might have a better time using https://vitest.dev/ as it has built-in TypeScript and ESM support

[blva]

Don't have strong feelings about this but we might have a better time using https://vitest.dev/ as it has built-in TypeScript and ESM support

no strong opinions on my side as well, is it something we use in other js repos within MDB? if so I'm happy to shift!

[gagik]

@blva It's newer so doesn't seem to be used by other projects much; I originally was gonna suggest mocha as that's what we use in other repos but actually jest seems simpler to setup for our purpose right now. Thinking more, maybe let's just stick to jest since the basic configuration looks already done anyhow

[blva]

@blva It's newer so doesn't seem to be used by other projects much; I originally was gonna suggest mocha as that's what we use in other repos but actually jest seems simpler to setup for our purpose right now. Thinking more, maybe let's just stick to jest since the basic configuration looks already done anyhow

cool! I'll continue with this then, I'd rather stick with technologies we've been working with for now, so jest it is and we can revisit!

[blva]

auto-generated via npm init jest@latest, we can clean up the comments

[blva]

adding a smalll test for now so that we can add tests in next PRs and I'll slowly backfill tests

[Copilot]

Copilot reviewed 6 out of 8 changed files in this pull request and generated 1 comment.

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• package.json: Language not supported
• tsconfig.jest.json: Language not supported

[fmenezes]

this is actually contradicting main tsconfig.json, do we need it?

[blva]

we need the module, but I can update to esnext as it seems to work

[blva]

sorry actually, we can't use nodenext here, it doesn't work well w/ isolated modules, but esnext works

[gagik]

@blva https://jestjs.io/docs/ecmascript-modules Seems like ESM support is experimental in Jest.
With us using "type": "module" (which we should because ESM is what's recommended now, CommonJS is more of a legacy thing). We can either
a) continue trying with Jest, I think some configuration is possible with ESM but it does seem like library mocking is not going to be great regardless with our setup.
b) maybe use Mocha + Chai + Sinon as they do support ESM and would also be more consistent with rest of DevTools. If you need help setting this up let me know, I could create a PR copying some of the mongosh configuration.

[gagik]

@blva I opened #50 to try to see how Mocha goes, it actually seems simpler to set up because of the ESM stuff, wasn't too familiar with how jest was working with it. Let me know what you think

[blva]

@gagik works for me, can you fix the tests in the PR so we can merge to start adding mroe tests

[gagik]

@blva Actually upon further investigation, I think this is actually the best experience after all, mocha isn't much different 😅 Sorry for the bunch of back and forth, was just trying to make sure we're not regressing the TS setup but this should work best.

If we can rename __tests__/ => tests/, LGTM