test: strengthen worklet runtime guardrails

[Yradex]

Summary by CodeRabbit

• Tests
  • Expanded worklet compilation test coverage with new validation scenarios for distinct worklet ID generation and runtime behavior.
  • Added comprehensive bundler output test suite validating worklet-runtime injection and registration lifecycle.
  • Consolidated worklet testing infrastructure with centralized test configuration.

Summary

• strengthen the worklet transform guardrails with targeted positive and negative assertions around runtime injection
• add bundler guardrails for worklet-runtime emission, single runtime-body injection, and unique main-thread worklet registrations
• expand runtime and testing-library guardrails for duplicate registration behavior and multiple main-thread worklets under background-thread mode

Testing

• CI=true pnpm vitest run __test__/fixture.spec.js -t worklet
• CI=true pnpm vitest run --project webpack/react test/worklet-runtime.test.ts test/cases.test.ts -t worklet-runtime
• CI=true pnpm vitest run __test__/workletRuntime.test.js __test__/runOnMainThread.test.js __test__/runOnBackground.test.js
• CI=true pnpm vitest run src/__tests__/worklet.test.jsx

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).
• Changeset added, and when a BREAKING CHANGE occurs, it needs to be clearly marked (or not required).

[changeset-bot]

⚠️ No Changeset found

Latest commit: cdf5f12

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: b27850d4-7e57-47c1-8d85-60b8abf72f0b

📥 Commits

Reviewing files that changed from the base of the PR and between 421ce08 and cdf5f12.

📒 Files selected for processing (1)

• packages/react/worklet-runtime/__test__/workletRuntime.test.js

✅ Files skipped from review due to trivial changes (1)

• packages/react/worklet-runtime/test/workletRuntime.test.js

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📝 Walkthrough

Walkthrough

Tests added across multiple packages to verify worklet compilation into distinct instances, worklet registration overwriting behavior, and bundler integration correctly including or excluding worklet-runtime based on usage patterns. Test logic migrated from scattered test case files to a centralized bundler guardrails test suite.

Changes

Cohort / File(s)	Summary
Testing-library worklet tests packages/react/testing-library/src/__tests__/worklet.test.jsx	Added test asserting multiple main-thread worklet handlers compile into distinct worklets with unique IDs and trigger only their respective callbacks.
Transform test suite packages/react/transform/__test__/fixture.spec.js	Extended test assertions to verify runtime injection (loadWorkletRuntime, registerWorkletInternal) presence for LEPUS/MIXED targets and absence for JS target; added quantitative occurrence validation.
Worklet-runtime unit tests packages/react/worklet-runtime/__test__/workletRuntime.test.js	Added test validating that registering the same worklet ID overwrites prior registration, ensuring only the latest handler executes.
Webpack plugin test case restructuring packages/webpack/react-webpack-plugin/test/cases/worklet-runtime/chunk/{a.jsx, index.js, test.config.cjs}, packages/webpack/react-webpack-plugin/test/cases/worklet-runtime/not-using/{index.js, test.config.cjs}	Migrated test logic from test case modules to centralized suite; added onLongPressMT handler in fixture; cleared bundlePath expectations to delegate assertions elsewhere.
Webpack plugin bundler guardrails test packages/webpack/react-webpack-plugin/test/worklet-runtime.test.ts	Added comprehensive test suite validating worklet-runtime bundler integration: extracts worklet IDs from bundles, verifies initialization signature occurrence counts, and validates presence/absence of worklet-runtime chunks.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

Possibly related PRs

• fix(react): use correct @lynx-js/react/worklet-runtime #1711 — Changes worklet-runtime resolution and injection in the webpack plugin, directly related to bundler integration.
• feat(react): shared runtime imports #1968 — Modifies the transform test suite with worklet/runtime-related assertions, overlapping test scope.
• fix(react/runtime): prevent reloadVersion from cancelling the MTRef initial value patch #1757 — Updates the same worklet testing-library test file with worklet runtime behavior validations.

Suggested reviewers

• hzy
• gaoachao
• upupming

Poem

🐰 Worklets dancing, each unique and bright,
IDs compiled in the main-thread light,
Registration overwrites the old with new,
Bundler checks pass—our tests ring true!
Hopping forward, robust and right! 🚀

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'test: strengthen worklet runtime guardrails' directly and clearly describes the main objective of the pull request—adding and enhancing test guardrails for worklet runtime behavior across multiple test files and bundles.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

📢 Thoughts on this report? Let us know!

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/react/worklet-runtime/src/workletRuntime.ts`:
- Around line 18-20: The initWorklet reset only clears the top-level
workletCache but doesn’t address nested child contexts that
transformWorkletInner in runWorklet rewrites by replacing nested _wkltId entries
with bound functions (leaving stale child worklets in reused ctxs via
_c/params). Fix by preserving or cloning the original nested worklet ctx
templates before any transformation and/or maintaining a registry mapping of
original ctx templates keyed by _wkltId so initWorklet can rebuild nested ctxs
from those templates; update initWorklet to iterate the registry and restore
nested ctxs (or clear transformed children) so entries referenced by _c and
params are re-resolved against the fresh registry rather than calling pre-init
bound functions (refer to initWorklet, workletCache, runWorklet,
transformWorkletInner, _wkltId, _c, params, and globalThis.lynxWorkletImpl).

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 8c3e325e-cb45-405e-af36-58d46ff07cdf

📥 Commits

Reviewing files that changed from the base of the PR and between 518c310 and 421ce08.

📒 Files selected for processing (10)

• packages/react/testing-library/src/__tests__/worklet.test.jsx
• packages/react/transform/__test__/fixture.spec.js
• packages/react/worklet-runtime/__test__/workletRuntime.test.js
• packages/react/worklet-runtime/src/workletRuntime.ts
• packages/webpack/react-webpack-plugin/test/cases/worklet-runtime/chunk/a.jsx
• packages/webpack/react-webpack-plugin/test/cases/worklet-runtime/chunk/index.js
• packages/webpack/react-webpack-plugin/test/cases/worklet-runtime/chunk/test.config.cjs
• packages/webpack/react-webpack-plugin/test/cases/worklet-runtime/not-using/index.js
• packages/webpack/react-webpack-plugin/test/cases/worklet-runtime/not-using/test.config.cjs
• packages/webpack/react-webpack-plugin/test/worklet-runtime.test.ts

[codspeed-hq]

Merging this PR will improve performance by ×4.3

⚡ 1 improved benchmark
✅ 62 untouched benchmarks
⏩ 21 skipped benchmarks¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	basic-performance-large-css	67.9 ms	15.8 ms	×4.3

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_{Comparing Yradex:wt/move-mts-runtime-2-20260319 (cdf5f12) with main (fcda36a)}

Footnotes

1. 21 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. ↩

[relativeci]

Web Explorer

#8398 Bundle Size — 724.73KiB (0%).

cdf5f12(current) vs 36b38eb main#8397(baseline)

Bundle metrics   1 change

	Current #8398	Baseline #8397
Initial JS	41.99KiB	41.99KiB
Initial CSS	1.99KiB	1.99KiB
Cache Invalidation	0%	0%
Chunks	8	8
Assets	10	10
Modules	150(+0.67%)	149
Duplicate Modules	11	11
Duplicate Code	34.75%	34.75%
Packages	3	3
Duplicate Packages	0	0

Bundle size by type  no changes

	Current #8398	Baseline #8397
Other	382.38KiB	382.38KiB
JS	340.36KiB	340.36KiB
CSS	1.99KiB	1.99KiB

Bundle analysis report Branch Yradex:wt/move-mts-runtime-2-202... Project dashboard

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