fix(rstest): prevent the re-exports optimization for mocked modules by 9aoy · Pull Request #13262 · web-infra-dev/rspack

9aoy · 2026-03-09T09:56:06Z

Summary

When modules are marked as side-effect-free, Rspack may inline re-export chains and skip intermediate modules. That can break rs.mock() / rs.doMock() when users mock the intermediate package name (the mocked module ID is no longer the one consumers execute).

This change marks mocked modules as non-side-effect-free during optimize_dependencies, so module boundaries are preserved and mocks reliably hit the intended module IDs.

Added an optimize_dependencies hook in RstestPlugin (stage = -1000) to run before side-effects optimization.
Collected all modules referenced by DependencyType::RstestMockModuleId (covers both rs.mock and rs.doMock).
For those modules, if factory_meta.side_effect_free == Some(true), override to Some(false).

Checklist

Tests updated (or not required).
Documentation updated (or not required).

Copilot

Pull request overview

This PR fixes an rstest mocking edge case where side-effects optimization can inline re-export chains and skip intermediate modules, causing rs.mock() / rs.doMock() to miss the intended module IDs. It does so by ensuring modules referenced by rstest mock-module-id dependencies are treated as non-side-effect-free during optimize_dependencies, and adds regression tests covering re-export chains.

Changes:

Add an early CompilationOptimizeDependencies hook in RstestPlugin to mark mocked modules as not side-effect-free.
Add new rstest config-case entries and test specs for mocking through single and multi-hop re-export chains.
Add local node_modules/* fixtures (reexport-top, reexport-intermediate, reexport-source) to reproduce sideEffects-driven re-export inlining.

Reviewed changes

Copilot reviewed 6 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/rspack-test/configCases/rstest/mock/rspack.config.js	Adds new rstest entries to run the added re-export mocking regression tests.
tests/rspack-test/configCases/rstest/mock/reExportMockedModule.js	New regression test: `rs.mock()` against a side-effect-free re-exported package.
tests/rspack-test/configCases/rstest/mock/reExportDoMockedModule.js	New regression test: `rs.doMock()` against a side-effect-free re-exported package.
tests/rspack-test/configCases/rstest/mock/reExportTripleMockedModule.js	New regression test: `rs.mock()` across A→B→C re-export chain.
tests/rspack-test/configCases/rstest/mock/reExportTripleDoMockedModule.js	New regression test: `rs.doMock()` across A→B→C re-export chain.
tests/rspack-test/configCases/rstest/mock/node_modules/reexport-top/package.json	Fixture package marked `sideEffects: false` to trigger side-effects optimization behavior.
tests/rspack-test/configCases/rstest/mock/node_modules/reexport-top/index.js	Fixture top package that re-exports from `reexport-intermediate`.
tests/rspack-test/configCases/rstest/mock/node_modules/reexport-intermediate/package.json	Fixture package marked `sideEffects: false` to trigger re-export inlining.
tests/rspack-test/configCases/rstest/mock/node_modules/reexport-intermediate/index.js	Fixture intermediate package that re-exports from `reexport-source`.
tests/rspack-test/configCases/rstest/mock/node_modules/reexport-source/package.json	Fixture “real implementation” package metadata.
tests/rspack-test/configCases/rstest/mock/node_modules/reexport-source/index.js	Fixture “real implementation” export.
crates/rspack_plugin_rstest/src/plugin.rs	Adds `optimize_dependencies` hook to flip side-effect-free flags for mocked modules.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.

crates/rspack_plugin_rstest/src/plugin.rs

github-actions · 2026-03-09T10:07:22Z

📦 Binary Size-limit

Comparing 88223d5 to perf: remove ukey collections (#13309) by harpsealjs

❌ Size increased by 4.88KB from 48.99MB to 49.00MB (⬆️0.01%)

github-actions · 2026-03-09T10:08:31Z

Rsdoctor Bundle Diff Analysis

⚠️ Note: The latest commit (3a5fc54ceb) does not have baseline artifacts. Using commit 9f580f5543 for baseline comparison instead. If this seems incorrect, please wait a few minutes and try rerunning the workflow.

Found 5 projects in monorepo, 0 projects with changes.

📊 Quick Summary

Project	Total Size	Change
react-10k	5.7 MB	0
react-1k	826.2 KB	0
react-5k	2.7 MB	0
rome	984.2 KB	0
ui-components	2.3 MB	0

Generated by Rsdoctor GitHub Action

codspeed-hq · 2026-03-09T10:12:44Z

Merging this PR will not alter performance

✅ 16 untouched benchmarks
⏩ 3 skipped benchmarks¹

_{Comparing mock-with-re-export (88223d5) with main (9f580f5)}

3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

cloudflare-workers-and-pages · 2026-03-12T04:00:18Z

Deploying rspack with Cloudflare Pages

Latest commit:	`1c2bde9`
Status:	✅ Deploy successful!
Preview URL:	https://a5de4d39.rspack-v2.pages.dev
Branch Preview URL:	https://mock-with-re-export.rspack-v2.pages.dev

View logs

github-actions · 2026-03-12T05:02:59Z

📝 Ecosystem CI detail: Open

suite	result
rstest	✅ success
plugin	✅ success
rslib	✅ success
rsdoctor	❌ failure
nuxt	❌ failure
devserver	❌ failure
rspress	❌ failure
rsbuild	✅ success
lynx-stack	❌ failure
examples	❌ failure
modernjs	❌ failure

9aoy added 3 commits March 9, 2026 17:22

feat(rstest): mock should work with re-export module

0a850f9

test: update

20433ee

fix: hoist check

21a0ece

Copilot AI review requested due to automatic review settings March 9, 2026 09:56

9aoy requested a review from LingyuCoder as a code owner March 9, 2026 09:56

github-actions bot added release: bug fix release: bug related release(mr only) team The issue/pr is created by the member of Rspack. labels Mar 9, 2026

Copilot started reviewing on behalf of 9aoy March 9, 2026 09:58 View session

Copilot AI reviewed Mar 9, 2026

View reviewed changes

crates/rspack_plugin_rstest/src/plugin.rs Outdated Show resolved Hide resolved

9aoy added 3 commits March 9, 2026 18:39

fix: lint

ac29898

Merge branch 'main' into mock-with-re-export

18382f1

Merge branch 'main' into mock-with-re-export

1c2bde9

Merge branch 'main' into mock-with-re-export

88223d5

9aoy enabled auto-merge (squash) March 12, 2026 08:13

fi3ework approved these changes Mar 12, 2026

View reviewed changes

9aoy merged commit 802fca1 into main Mar 12, 2026
74 of 76 checks passed

9aoy deleted the mock-with-re-export branch March 12, 2026 08:17

web-infra-dev deleted a comment from github-actions bot Mar 18, 2026

This was referenced Mar 18, 2026

docs: remove mocking re-exported modules tip web-infra-dev/rstest#1069

Merged

chore(rstest-skill): remove ProvidedExports Troubleshooting rstackjs/agent-skills#35

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

fix(rstest): prevent the re-exports optimization for mocked modules#13262

fix(rstest): prevent the re-exports optimization for mocked modules#13262
9aoy merged 7 commits intomainfrom
mock-with-re-export

9aoy commented Mar 9, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

github-actions bot commented Mar 9, 2026 •

edited

Loading

Uh oh!

github-actions bot commented Mar 9, 2026 •

edited

Loading

Uh oh!

codspeed-hq bot commented Mar 9, 2026 •

edited

Loading

Uh oh!

cloudflare-workers-and-pages bot commented Mar 12, 2026 •

edited

Loading

Uh oh!

github-actions bot commented Mar 12, 2026 •

edited

Loading

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Uh oh!

Conversation

9aoy commented Mar 9, 2026

Summary

Related links

Checklist

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

github-actions bot commented Mar 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

📦 Binary Size-limit

Uh oh!

github-actions bot commented Mar 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Rsdoctor Bundle Diff Analysis

Uh oh!

codspeed-hq bot commented Mar 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Merging this PR will not alter performance

Footnotes

Uh oh!

cloudflare-workers-and-pages bot commented Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Deploying rspack with Cloudflare Pages

Uh oh!

github-actions bot commented Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

github-actions bot commented Mar 9, 2026 •

edited

Loading

github-actions bot commented Mar 9, 2026 •

edited

Loading

codspeed-hq bot commented Mar 9, 2026 •

edited

Loading

cloudflare-workers-and-pages bot commented Mar 12, 2026 •

edited

Loading

github-actions bot commented Mar 12, 2026 •

edited

Loading