Repository navigation
Conversation
In native ESM, `import * as fs` is a read-only module namespace, so patching it threw `Cannot assign to read only property`. Patch the mutable CJS `fs` object behind the default export instead, and sync builtin ESM exports so named imports see the wrappers. The fs integration tests now also run in ESM. Fixes #25950 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Member
Author
|
bugbot run |
![github-advanced-security[bot]](https://avatars.githubusercontent.com/in/57789?s=60&v=4){kind=small}
Contributor
size-limit report 📦Compared: fc15b78 (PR test merge using develop at b9d0f82) Against: b9d0f82 (develop) · base run #64917 ✅ Baseline matches: this diff contains only this PR's changes.
|
![cursor[bot]](https://avatars.githubusercontent.com/in/1210556?s=60&v=4){kind=small}
Contributor
Optional E2E testsSome optional checks were not successful. They do not block the merge. 3 not successful, 41 successful. See the run.
Successful checks
|
The Bun build project runs a bundled scenario outside the test's tmp dir, so a path derived from the scenario location missed the fixtures. Also skip the ESM tests on Bun, whose ESM `node:fs` exports behave like Deno's. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Member
Author
|
bugbot run |
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Member
Author
|
bugbot run |
There was a problem hiding this comment.
✅ Bugbot reviewed your changes and found no new issues!
Comment @cursor review or bugbot run to trigger another review on this PR
Reviewed by Cursor Bugbot for commit ded32e7. Configure here.
chargome
marked this pull request as ready for review
November 4, 2026 09:23
chargome
requested review from
andreiborza and
mydea
and removed request for
a team
November 4, 2026 09:23
mydea
reviewed
Nov 4, 2026
| const createRunner = (): ReturnType<typeof createTestRunner> => | ||
| createTestRunner().withEnv({ FIXTURES_DIR: join(cwd, 'fixtures') }); | ||
| // On Bun and Deno the ESM `node:fs` exports are not tied to the `fs` object we patch, so only `fs.promises` is traced there. | ||
| const testUnlessNonNodeEsm = test.runIf(mode === 'cjs' || supports({ runtimes: ['node'] })); |
Member
There was a problem hiding this comment.
no strong feelings, but would it be good enough to just only run these tests in cjs...? 🤔
Member
Author
There was a problem hiding this comment.
Hm this would defeat the purpose of the pr then, since it is about native esm?
This branch has not been deployed
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Why: In native ESM,
fsIntegrationcrashed withCannot assign to read only property, because it patched the read-onlyimport * as fsnamespace. It now patches the mutablefsobject behind the default export. A plainimport fs from 'fs'isn't an option: our rollupinterop: 'esModule'setting would turn it intorequire('fs').defaultin the CJS build, which is undefined. After patching, it callssyncBuiltinESMExports()so named imports (import { readFile } from 'fs') pick up the patched functions. That call is wrapped in try/catch because Cloudflare workerd exports it but throws when it's called.How to review: The fix is in
instrumentation.ts. The fs suite now runs in both ESM and CJS. On Bun and Deno, the ESMnode:fsexports aren't tied to the object we patch, so onlyfs.promisescalls get spans there. For that reason those ESM tests run on Node only. The named-import test is ESM-only, because CJS destructuring copies the functions before the patch is applied.Unsure about:
syncBuiltinESMExports()updates the ESM exports of every builtin module, not onlyfs. It only makes patches applied to the CJS objects visible to ESM importers, so it shouldn't affect anything else.Closes #25950