Support for vite@6 async plugins

[manuel3108]

Describe the bug

Using @sveltejs/kit@2.9.0 and vitest@2.1.8 makes tsc fail with the following vite.config.ts

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

export default defineConfig({
    plugins: [sveltekit()],
});

Problem was first reported in sveltejs/cli#341. While a user is adding vitest to his project, we are switching out the imports inside vite.config.ts like this:

// without vitest
import { defineConfig } from 'vite';

// with vitest
import { defineConfig } from "vitest/config";

This is likely caused by vite@6 allowing plugins of type Promise<whatever>. Looks like this change was not backported to config used by vitest

Reproduction

https://stackblitz.com/edit/node-zjetgl?file=vite.config.ts

Wait for npm i to complete. Run npm run check. The issue will appear. IntelliSense also complains

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    vite: ^6.0.0 => 6.0.2 
    vitest: ^2.1.8 => 2.1.8

Used Package Manager

npm

Validations

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• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
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• The provided reproduction is a minimal reproducible example of the bug.

[manuel3108]

I was just made aware of that this was reverted as part of https://github.com/vitest-dev/vitest/releases/tag/v2.1.7, but i would still keep this issue open, as i was unable to find any other issue that's referencing vite 6 support.

But please feel free to close.

[niemyjski]

2.1.7 broke npm run check for us:

import { sveltekit } from '@sveltejs/kit/vite';
import Icons from 'unplugin-icons/vite';
import { defineConfig } from 'vitest/config';

const aspNetConfig = getAspNetConfig();

export default defineConfig({
    build: {
        sourcemap: true,
        target: 'esnext'
    },
    plugins: [
        sveltekit(),
        Icons({
            compiler: 'svelte'
        })
    ],

Exceptionless\src\Exceptionless.Web\ClientApp\vite.config.ts:14:9
Error: No overload matches this call.
  The last overload gave the following error.
    Type 'Promise<Plugin<any>[]>' is not assignable to type 'PluginOption'.
      Type 'Promise<Plugin<any>[]>' is not assignable to type 'Promise<false | Plugin<any> | PluginOption[] | null | undefined>'.
        Type 'Plugin<any>[]' is not assignable to type 'false | Plugin<any> | PluginOption[] | null | undefined'.
          Type 'Plugin<any>[]' is not assignable to type 'PluginOption[]'.
            Type 'Plugin<any>' is not assignable to type 'PluginOption'.

[sheremet-va]

Vitest 2 doesn't support Vite 6 and will not support Vite 6 officially. You can use resolutions or pnpm.overrides to change the version range locally, Vite 6 API is the same and should work for Vitest 2.

If you migrated to Vite 6, use Vitest 3 (currently in beta), release is planned for January.

If you see any type errors in your config, check the lockfile to confirm that you have several Vite versions installed and resolve it with your package manager.