tsdown support?

[synecdokey]

Right now, vitest can infer its build parameters based on a vite.config.ts file, but it doesn't seem to for a tsdown.config.ts.

The main issue is that tsdown relies more on conventions and inference, so a lot of things aren't explicitly in the config either.

Has someone found a good way to make them play nice with each other and ensure I am testing the code as it is built for consumers, and not how vitest builds it instead?

[hi-ogawa]

The direction wise, it's actually aimed to be opposite where tsdown infers vite or vitest config. https://tsdown.dev/options/config-file#extending-vite-or-vitest-config-experimental

Can you explain what config specifically you want to deduplicate between two configs? I think only thing matters is rollup/down plugins.

[synecdokey]

Yeah, so it's inverted compared to how vitest integrates with vite: https://vitest.dev/guide/#configuring-vitest which is the model that makes sense, the bundler should be caring about how to build things, and the testing should piggyback on that.

The main issue with that inversion is that it means a lot more things need to be explicit, since tsdown will infer a lot of settings, such as whether to use a react plugin, what kind of typescript compilation to do, which vitest doesn't (and shouldn't?) do. It's also a big shift compared to the "old" way.