Configuration for vitest not assignable to type UserConfig

[Beiri22]

Describe the bug

There seems to be some configuration deficiency. See below.

Reproduction

Create a standard sveltekit project including vitest.

You get a vite.config like:

import { sveltekit } from '@sveltejs/kit/vite';
import type { UserConfig } from 'vite';

const config: UserConfig = {
	plugins: [sveltekit()],
	test: {
		include: ['src/**/*.{test,spec}.{js,ts}']
	}
};

export default config;

running npm run check states the problem:

Error: Type '{ plugins: Promise<Plugin_2[]>[]; test: { include: string[]; }; }' is not assignable to type 'UserConfig'.
  Object literal may only specify known properties, and 'test' does not exist in type 'UserConfig'. 
        plugins: [sveltekit()],
        test: {
                include: ['src/**/*.{test,spec}.{js,ts}']
        }
};

Logs

No response

System Info

System:
    OS: Linux 6.2 Manjaro Linux
    CPU: (16) x64 Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz
    Memory: 25.43 GB / 31.27 GB
    Container: Yes
    Shell: 3.6.0 - /usr/bin/fish
  Binaries:
    Node: 19.4.0 - /usr/bin/node
    Yarn: 1.22.19 - /usr/bin/yarn
    npm: 8.19.2 - /usr/bin/npm
  Browsers:
    Chromium: 109.0.5414.119
    Firefox: 109.0
  npmPackages:
    @sveltejs/adapter-node: ^1.0.0 => 1.1.4 
    @sveltejs/kit: ^1.0.0 => 1.3.2 
    svelte: ^3.54.0 => 3.55.1 
    vite: ^4.0.0 => 4.0.4

Severity

annoyance

Additional Information

No response

[dominikg]

following https://vitest.dev/config/ you can do

import { sveltekit } from '@sveltejs/kit/vite';
import { defineConfig } from 'vitest/config';

export default defineConfig({
	plugins: [sveltekit()],
	test: {
		include: ['src/**/*.{test,spec}.{js,ts}']
	}
})

edit: which would be nice if it was set up by create-svelte automatically when you pick vitest

[Beiri22]

I will try that. I also would appreciate it being set up correctly by create-svelte.

I just thought of other unseen conflicts of vite/config and vitest/config. Is vitest/config a superset of vite/config or is there any property lost when changing to it.

[dominikg]

should be a superset.

[Beiri22]

And could there be other frameworks (like vitest) that superset the vite configuration, so that conflicts appear? So maybe some type magic will open this up for later extention?

import { sveltekit } from '@sveltejs/kit/vite';
import type { UserConfig as ViteConfig } from 'vite';
import type { UserConfig as VitestConfig } from 'vitest/config';

const config: ViteConfig & VitestConfig = {
	plugins: [sveltekit()],
	test: {
		include: ['src/**/*.{test,spec}.{js,ts}']
	}
};
export default config;

[Rich-Harris]

Should we just always use defineConfig, and just vary whether it's imported from vite or vitest/config? Would be more consistent than only using defineConfig for vitest projects

[dominikg]

good idea, defineConfig is documented for vite https://vitejs.dev/config/#config-intellisense

it works with type inference too, so no additional type annotation needed