Cannot bundle built-in module "bun:test" since Vitest v4.0.0

[tpfaffenbauer]

Environment

• Operating System: Linux
• Node Version: v23.5.0
• Nuxt Version: 4.2.1
• CLI Version: 3.30.0
• Nitro Version: 2.12.9
• Package Manager: bun@1.3.2
• Builder: -
• User Config: compatibilityDate, devtools, modules
• Runtime Modules: @nuxt/test-utils/module@3.20.1
• Build Modules: -

Reproduction

https://github.com/tpfaffenbauer/ntu-bun-repro

Describe the bug

I've set up a new project this week with v3.20.1 and after following the installation instructions for @nuxt/test-utils I'm not able to run tests using bun run vitest due to the following error:

Error: Cannot bundle built-in module "bun:test" imported from "node_modules/@nuxt/test-utils/dist/shared/test-utils.CtoalVlS.mjs". Consider disabling environments.client.noExternal or remove the built-in dependency.

I noticed bun happily installs Vitest v4.0.0 without complaints even though the peer dependency is set to v3.2.0. npm refuses and installs v3.2.4 instead. When using bun, hard locking the Vitest version to v3.2.4 runs the test successfully. Is @nuxt/test-utils expected to work with Vitest 4 yet?

Additional context

No response

Logs

FAIL   nuxt  ../test/nuxt/someTest.test.ts [ test/nuxt/someTest.test.ts ]
Error: Cannot bundle built-in module "bun:test" imported from "node_modules/@nuxt/test-utils/dist/shared/test-utils.CtoalVlS.mjs". Consider disabling environments.client.noExternal or remove the built-in dependency.
  Plugin: vite:import-analysis
  File: /home/tom/ntu-repro/node_modules/@nuxt/test-utils/dist/shared/test-utils.CtoalVlS.mjs:117:31
  115 |  
  116 |  async function setupBun(hooks) {
  117 |    const bunTest = await import('bun:test');
      |                                 ^
  118 |    hooks.ctx.mockFn = bunTest.mock;
  119 |    bunTest.beforeAll(hooks.beforeAll);
 ❯ ResolveIdContext._formatLog ../node_modules/vite/dist/node/chunks/config.js:29618:43
 ❯ ResolveIdContext.error ../node_modules/vite/dist/node/chunks/config.js:29615:14
 ❯ ResolveIdContext.handler ../node_modules/vite/dist/node/chunks/config.js:33197:13
 ❯ EnvironmentPluginContainer.resolveId ../node_modules/vite/dist/node/chunks/config.js:29336:56
 ❯ TransformPluginContext.resolve ../node_modules/vite/dist/node/chunks/config.js:29548:13
 ❯ normalizeUrl ../node_modules/vite/dist/node/chunks/config.js:27730:22
 ❯ ../node_modules/vite/dist/node/chunks/config.js:27796:32
 ❯ TransformPluginContext.transform ../node_modules/vite/dist/node/chunks/config.js:27764:4
 ❯ EnvironmentPluginContainer.transform ../node_modules/vite/dist/node/chunks/config.js:29416:14

[matthew-dean]

I'm having this same issue. Seems that Nuxt test-utils are incompatible with the latest version of Vitest.

[victorgarciaesgi]

Reverting back to @nuxt/test-utils@3.17.2 works, since support for Bun landed in 3.18

[GonzoDivae]

It seems like setupBun is never executed, but still the import for 'bun:test' is done. Not sure where or how to fix it, but another workaround is to resolve the alias to some file, so the import runs successfully, even though it's never used. In vitest.config.ts:

import { defineVitestConfig } from '@nuxt/test-utils/config';
import { resolve } from 'node:path';

export default defineVitestConfig({
  resolve: {
    alias: {
      'bun:test': resolve('./vitest.config.ts'),
    },
  },
  // The rest of your vitest config
});

You could probably also point to an empty file, but it has to be a resolvable path to a file.

With that all my tests (also e2e tests) run just fine.

[Lenni009]

I still get the same error with Nuxt 4.3.1, @nuxt/test-utils 4.0.0 and Bun 1.3.9

[silvesterwali]

i also experience the same while just use nodejs

[Olympus5]

It works with vitest locked on version 3.x.x (and nuxt/test-utils to v3.23.0), and I think that's the only viable solution at the moment.

[BotellaA]

Is there a working solution that uses vitest 4?

[Aietes]

Hit this with @nuxt/test-utils@4.0.0 + Vitest 4 as well.

I think it happens because @nuxt/test-utils has a shared Bun setup path with:

await import('bun:test')

With Vitest 4 / Vite 7, Vite import-analysis tries to statically process that import in Node runs, then fails because bun:test is a Bun-only built-in.

Working fix

Change that import to a non-literal specifier so Vite doesn’t try to bundle it:

// before
await import('bun:test')

// after
await import(`bun${':'}test`)

This still resolves to bun:test at runtime in Bun, but avoids the Node/Vite transform crash.

Quick pnpm patch in a Nuxt project

pnpm patch @nuxt/test-utils@4.0.0

That prints a temp folder path. Edit this file in that folder: dist/shared/test-utils.E_cAGA8l.mjs.

Change:

await import('bun:test')

to:

await import(`bun${':'}test`)

Then commit the patch:

pnpm patch-commit <that-temp-folder>

pnpm will:

• create the patch file under patches/
• add/update pnpm.patchedDependencies in package.json
• update pnpm-lock.yaml

Finally run:

pnpm install

This removed the Cannot bundle built-in module "bun:test" error immediately for me.

[Gonzo17]

I've investigated this issue and it turns out that a test fails when it has an import on @nuxt/test-utils or @nuxt/test-utils/e2e (both point to the same file) AND environment nuxt.

Also worth to mention, because it confused me: If you set environment: 'node' inside of await defineVitestProject(...), it will be overriden to environment: 'nuxt'. (src/config.ts)

      await defineVitestProject({
        test: {
          name: 'e2e',
          include: ['test/e2e/**/*.{test,spec}.ts'],
          testTimeout: 60000,
          environment: 'node', // will be overriden by defineVitestProject to 'nuxt'
        },
      }),

Here an example on how it's intended: examples/app-vitest/vitest.config.ts

This issue also seems to be related to #1377

So it works as designed, it was just not clear what the design is. :) I think it would be nice to have some documentation on what defineVitestProject is intended for, because just from the name I didn't guess that it sets the environment. Maybe some JSDoc and a section in the Nuxt testing doc?

[DamianGlowala]

In the meanwhile, you can also add the following snippet to your Vitest config:

export default defineVitestConfig({
  plugins: [
    {
      name: 'ignore-bun-test',
      enforce: 'pre',
      resolveId(id) {
        if (id === 'bun:test') {
          return { id: 'bun:test', external: true }
        }
      }
    }
  ]
})

[Olympus5]

Thank @DamianGlowala, the workaround works for me. IMO, this is by far the best solution while waiting for a fix.