node:module: implement findPackageJSON

[eduardoaugustolb]

Fixes #23898.

Root cause

node:module did not export or implement findPackageJSON, so a named ESM import failed before the call could run.

Change

Expose a native findPackageJSON binding and resolve through Bun’s existing ESM resolver, returning the selected package’s package.json. This preserves ESM package resolution for bare specifiers and resolved file URLs.

Validation

The added regression test runs both findPackageJSON("pkg", import.meta.url) and the issue-shaped findPackageJSON(import.meta.resolve("pkg")). It fails on the unfixed system Bun with Export named 'findPackageJSON' not found in module 'node:module'.\n\nValidated in Docker:\n\nsh\nbun bd test test/js/node/module/node-module-module.test.js\n\n\nResult: 38 passed, 1 pre-existing skip.

[claude]

Claude Code Review

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📥 Commits

Reviewing files that changed from the base of the PR and between 315136d and 39b903f.

📒 Files selected for processing (5)

• src/jsc/NodeModuleModule.rs
• src/jsc/VirtualMachine.rs
• src/jsc/modules/NodeModuleModule.cpp
• src/resolver/result.rs
• test/js/node/module/node-module-module.test.js

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Walkthrough

Changes

The node:module API now exports findPackageJSON. Bun resolves package JSON paths from package specifiers and file URLs through a new resolver mode. Integration coverage verifies both lookup forms.

findPackageJSON resolution

Layer / File(s)	Summary
Package JSON resolution mode src/resolver/result.rs, src/jsc/VirtualMachine.rs	ResolveMode::PackageJson uses package JSON paths and returns empty paths for unsupported resolver results.
Native API bridge src/jsc/modules/NodeModuleModule.cpp, src/jsc/NodeModuleModule.rs	The host function validates arguments, converts file: URLs, delegates resolution, and returns the resolved path or undefined.
Integration validation test/js/node/module/node-module-module.test.js	The test verifies package-specifier and resolved-URL lookups for an ESM package.

Suggested reviewers: robobun, jarred-sumner, cirospaciari

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the implementation of findPackageJSON in node:module.
Description check	✅ Passed	The description explains the root cause, implementation, and validation, although it does not use the repository template headings.
Linked Issues check	✅ Passed	The changes export and implement findPackageJSON, support the reported call patterns, and add regression coverage for issue #23898.
Out of Scope Changes check	✅ Passed	The resolver, FFI, module export, result helper, and regression test changes all support the linked issue objectives.

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[robobun]

Thanks for this. I opened #37947, which keeps your commit as its first commit and reworks the lookup on top of it so it matches Node on the documented cases (for example findPackageJSON("..", import.meta.url), packages without a resolvable entry point, and the closest package.json for a resolved file). Details and the comparison against Node are in that PR's description.