resolve.tsconfigPaths: true not applied in test environment (Vite 8)

[ap-justin]

Describe the bug

Vite 8 introduces built-in tsconfig path resolution via resolve.tsconfigPaths: true. This works correctly during vite build and vite dev, but vitest does not pick it up — imports using tsconfig paths aliases fail to resolve during test runs.

Reproduction

tsconfig.json:

{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "#/*": ["src/*"],
      "@/*": ["lib/*"]
    }
  }
}

vite.config.ts:

import { defineConfig } from "vite";

export default defineConfig({
  resolve: { tsconfigPaths: true },
  test: {
    environment: "jsdom",
    globals: true,
  },
});

A test file importing #/services/foo fails with:

Error: Failed to resolve import "#/services/foo"

Adding vite-tsconfig-paths plugin resolves it:

import tsconfig_paths from "vite-tsconfig-paths";
export default defineConfig({
  plugins: [tsconfig_paths()],
  // ...
});

Expected behavior

resolve.tsconfigPaths: true should apply to both build and test environments, removing the need for vite-tsconfig-paths.

Actual behavior

Path aliases only resolve during build/dev. Tests fail with unresolved import errors.

Environment

• vitest: 4.1.2
• vite: 8.0.0
• OS: macOS
• Node: 24.x

---

Written by Claude

[github-actions]

Hello @ap-justin. Please provide a minimal reproduction using a GitHub repository or StackBlitz (you can also use examples). Issues marked with needs reproduction will be closed if they have no activity within 3 days.

[hi-ogawa]

Can you also prepare full reproduction code?

[MdSadiqMd]

Hey @ap-justin are you working on this issue?
If not @hi-ogawa can i work on this?

[AriPerkkio]

@MdSadiqMd feel free to help by setting up repository that reproduces the issue.

[MdSadiqMd]

Here is a reproduction: https://stackblitz.com/edit/vitest-dev-vitest-ukbynmwb

Expected behavior:

• When running npm run test:run -- test/tsconfig-paths.test.ts with plugins: [tsconfigPaths()] commented out in vite.config.ts, the test fails.
• When running the same command with plugins: [tsconfigPaths()] enabled, all tests pass

If this looks good, could you assign this issue to me so I can work on it?

cc: @AriPerkkio

[AriPerkkio]

Repro looks good to me.

We don't assign issues, feel free to work on it.

[hi-ogawa]

There is/was # alias issue in Vite 8 vitejs/vite#22038 Could be relevant.

[Bertie690]

Just going into the StackBlitz reproduction and changing the alias name a bunch, I'm 80% sure it's not related to what the actual makeup of the import alias is.

[MdSadiqMd]

@AriPerkkio
There is a check failing in the PR pipeline [CI / Browsers: node-24, windows-latest (pull_request)]. This does not seem to be caused by my PR, I think it’s a separate issue. Could you please take a look and review my PR?

[hi-ogawa]

@MdSadiqMd The reproduction your provided here #10054 (comment) is passing for me locally. Can you check it fails on latest Vite?

[MdSadiqMd]

Yes, the issue isn’t related to the latest Vite version (vite@8.0.7), it’s a problem with the version specified in the issue description, which is vite@8.0.0