`Unable to resolve path to module` on `bun` or modules with `bun:` prefix

[karlhorky]

Importing modules with bun: prefix (eg. bun:test) or bun itself with @types/bun installed results in a resolution error with import-x/no-unresolved

Unable to resolve path to module 'bun:test'. eslint import-x/no-unresolved

index.test.ts

import { expect, test } from 'bun:test';

test('2 + 2', () => {
  expect(2 + 2).toBe(4);
});

[karlhorky]

Configuration Solution / Workaround

If automating this based on the TS types in @types/bun is not possible / feasible / wanted, then one way that I've found to work around this is to use the ignore option of import-x/no-unresolved :

eslint.config.js

const configArray = [
    rules: {
      'import-x/no-unresolved':
-        'error',
+        [
+          'error',
+          {
+            ignore: ['^bun(:\\w+)?$'],
+          },
+        ],
    },
  },
];

Full config

import eslintTypescript from '@typescript-eslint/eslint-plugin';
import typescriptParser from '@typescript-eslint/parser';
import eslintImportX from 'eslint-plugin-import-x';
import globals from 'globals';

/** @type
 * {import('@typescript-eslint/utils/ts-eslint').FlatConfig.ConfigArray}
 * */
const configArray = [
  {
    // Lint common extensions by default with rules above
    files: [
      '**/*.js',
      '**/*.jsx',
      '**/*.cjs',
      '**/*.mjs',
      '**/*.ts',
      '**/*.tsx',
      '**/*.cts',
      '**/*.mts',
    ],
    languageOptions: {
      parser: typescriptParser,
      parserOptions: {
        project: './tsconfig.json',
        // typescript-eslint specific options
        warnOnUnsupportedTypeScriptVersion: true,
      },
      globals: {
        ...globals.browser,
        ...globals.node,
        ...globals.commonjs,
        ...globals.es2021,
        // Allow using React as a global without importing it
        React: true,
      },
    },
    plugins: {
      '@typescript-eslint': {
        rules: eslintTypescript.rules,
      },
      'import-x': eslintImportX,
    },
    settings: {
      'import-x/parsers': {
        '@typescript-eslint/parser': ['.ts', '.tsx'],
      },
      'import-x/resolver': {
        // Load <rootdir>/tsconfig.json
        typescript: true,
        node: true,
      },
    },
    rules: {
      // Error on imports that don't match the underlying file
      // system
      // https://github.com/un-ts/eslint-plugin-import-x/blob/master/docs/rules/no-unresolved.md
      'import-x/no-unresolved': [
        'error',
        {
          ignore: ['^bun:\\w+$'],
        },
      ],
    },
  },
];


export default configArray;

[SukkaW]

See also import-js/eslint-import-resolver-typescript#266

[SukkaW]

import { isBuiltin } from 'node:module'

console.log(isBuiltin('bun:sqlite'))
// In Node.js: false
// In Bun: true

Thus we can't use isBuiltin here as ESLint might still be running under Node.js rather than Bun (E.g. in IDE).

[karlhorky]

Ah just saw this other PR:

• fix: ignore bun built-in modules import-js/eslint-import-resolver-typescript#288

I guess once this is published and eslint-plugin-import-x upgrades to it, it will resolve the issue

[SukkaW]

@karlhorky You don't have to upgrade eslint-plugin-import-x. You only need to upgrade eslint-import-resolver-typescript.

I just became the co-maintainer of eslint-import-resolver-typescript and I will release a new version of eslint-import-resolver-typescript as soon as possible.

[SukkaW]

The latest version of eslint-import-resolver-typescript (which was released about 15 hours ago) should have fixed the issue.

[karlhorky]

@SukkaW thanks for the heads up!

Yeah indeed, I can confirm that eslint-import-resolver-typescript@3.6.3 resolves the issue 🎉

Relevant PR from @SunsetTechuila :

• fix: ignore bun built-in modules import-js/eslint-import-resolver-typescript#288

This uses the new is-bun-module package (GitHub), nice 👀

cc @Jarred-Sumner

[karlhorky]

Ah, just upgraded dependencies and received Unable to resolve path to module 'bun:test' from import-x/no-unresolved again:

$ yarn eslint . --max-warnings 0
$ /home/runner/work/courses/courses/node_modules/.bin/eslint . --max-warnings 0
/home/runner/work/courses/courses/packages/curriculum-versions/curriculumVersions/2024-3-fall-pern-extensive-eu/drone/__tests__/smokeTest.test.ts
Error:   2:30  error  Unable to resolve path to module 'bun:test'  import-x/no-unresolved
/home/runner/work/courses/courses/packages/curriculum-versions/curriculumVersions/2025-1-winter-pern-extensive-eu/drone/__tests__/smokeTest.test.ts
Error:   2:30  error  Unable to resolve path to module 'bun:test'  import-x/no-unresolved
/home/runner/work/courses/courses/packages/fusion.upleveled.io/__tests__/smokeTestDevServer.test.ts
Error:   6:30  error  Unable to resolve path to module 'bun:test'  import-x/no-unresolved
/home/runner/work/courses/courses/packages/learn.upleveled.io/__tests__/smokeTestDevServer.test.ts
Error:   6:30  error  Unable to resolve path to module 'bun:test'  import-x/no-unresolved

Looking into the last dependency changes, it appears that eslint-import-resolver-typescript@4.2.0 caused this change:

Minor Changes

• feat: make is-bun-module as optional peer dependency import-js/eslint-import-resolver-typescript#391 c8121e5 Thanks @JounQin! - feat: make is-bun-module as optional peer dependency

Technically this is a BREAKING CHANGE, but considering we just raise out v4 recently and this only affects bun users, bun --bun eslint even works without this dependency, so I'd consider this as a minor change.

So for bun users, there are three options:

1. install is-bun-module dependency manually and use bun: true option
2. run eslint with bun --bun eslint w/o bun: true option
3. enable run#bun in bunfig.toml w/o bun: true option

@JounQin @SukkaW should this be added to the readme of eslint-plugin-import-x?

[JounQin]

@karlhorky Sorry for breaking, feel free to PR!

And considering import-js/eslint-import-resolver-typescript#402 will be released soon, some doc changes would be needed.

---

eslint-import-resolver-typescript v4.2.3 has just been released.

[karlhorky]

@JounQin thanks for the release!

I'll try to track down what changes are needed (maybe even code changes to eslint-plugin-import-x?

Some things which I tried so far which didn't work:

1. Adding is-bun-module as a dependency
2. Upgrading to eslint-import-resolver-typescript@4.2.3

[JounQin]

@karlhorky No change needed in eslint-plugin-import-x.

Did you enable bun: true option for eslint-import-resolver-typescript? Or just try bun --bun eslint?