[miniflare] fix: allow relative modules scriptPath outside of CWD

[mrbbot]

Fixes #4721.

What this PR solves / how to test:

Previously, Miniflare would resolve relative scriptPaths against moduleRoot multiple times resulting in incorrect paths and module names. This would lead to can't use ".." to break out of starting directory workerd errors. This change ensures Miniflare uses scriptPath as is, and only resolves it relative to modulesRoot when computing module names. Note this bug didn't affect service workers. This allows you to reference a modules scriptPath outside the working directory with something like:

const mf = new Miniflare({
	modules: true,
	modulesRoot: "..",
	scriptPath: "../worker.mjs",
});

Notably, this wasn't a problem if modulesRoot and scriptPath were absolute paths.

Author has addressed the following:

• Tests
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• Changeset (Changeset guidelines)
  • Included
  • Not necessary because:
• Associated docs
  • Issue(s)/PR(s):
  • Not necessary because: fixing a bug

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[changeset-bot]

🦋 Changeset detected

Latest commit: 24a068a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
miniflare	Patch
@cloudflare/pages-shared	Patch
wrangler	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[mrbbot]

I think this change is safe to make. Resolving to the modulesRoot root isn't correct here if modulePath is relative. If modulePath were absolute, this call would do nothing anyways.

[petebacondarwin]

Right. scriptPath should always be relative to cwd (or script:NN if provided inline). So if you wanted to force this to be absolute you would be more likely wanting to do only path.resolve(modulePath).

Interestingly, I assumed that this function would be recursive but it isn't. It is only called in getWorkerScript().

[mrbbot]

Yep, the mutually recursive functions are #visitJavaScriptModule() and #visitModule() below. 👍

[github-actions]

A wrangler prerelease is available for testing. You can install this latest build in your project with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/7831766474/npm-package-wrangler-4954

You can reference the automatically updated head of this PR with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/prs/4954/npm-package-wrangler-4954

Or you can use npx with this latest build directly:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/7831766474/npm-package-wrangler-4954 dev path/to/script.js

Additional artifacts:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/7831766474/npm-package-create-cloudflare-4954 --no-auto-update

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/7831766474/npm-package-miniflare-4954

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/7831766474/npm-package-cloudflare-pages-shared-4954

Note that these links will no longer work once the GitHub Actions artifact expires.

---

wrangler@3.27.0 includes the following runtime dependencies:

Package	Constraint	Resolved
miniflare	workspace:*	3.20240129.1
workerd	1.20240129.0	1.20240129.0
workerd --version	1.20240129.0	2024-01-29

Please ensure constraints are pinned, and miniflare/workerd minor versions match.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (0699506) 70.48% compared to head (24a068a) 70.49%.
Report is 384 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4954      +/-   ##
==========================================
+ Coverage   70.48%   70.49%   +0.01%     
==========================================
  Files         295      295              
  Lines       15407    15407              
  Branches     3948     3948              
==========================================
+ Hits        10859    10861       +2     
+ Misses       4548     4546       -2     

see 3 files with indirect coverage changes

[RamIdeas]

could we avoid the cwd change+resetting by choosing another tmp dir for the worker and using a relative path from the cwd to the other tmp dir?

[mrbbot]

Yeah, we could. Was keen to test this behaviour using the CWD specifically since it's very simple, and is what users are most likely to hit. The useCwd() implementation is actually from #4795, which uses it for some other tests too, so we're not just adding it for this. 👍

[petebacondarwin]

Right. scriptPath should always be relative to cwd (or script:NN if provided inline). So if you wanted to force this to be absolute you would be more likely wanting to do only path.resolve(modulePath).

Interestingly, I assumed that this function would be recursive but it isn't. It is only called in getWorkerScript().