feat(coverage): v8 to track `node:child_process` and `node:worker_threads` contexts by AriPerkkio · Pull Request #9976 · vitest-dev/vitest

AriPerkkio · 2026-03-26T13:36:55Z

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commit: cc332ea

AriPerkkio · 2026-04-12T10:27:54Z

 import { loadProvider } from './load-provider'

-const session = new inspector.Session()
+let session: inspector.Session | null = null


This used to create unused new Session() on main thread too, oops.

AriPerkkio · 2026-04-13T10:57:16Z


 Collect coverage only for files changed since a specified commit or branch. When set to `true`, it uses staged and unstaged changes.
+
+## coverage.trackProcessAndWorker


Naming this option is difficult. Right now it only covers node:child_process and node:worker_threads, but in future it's likely going to be used for web workers and similar on browser. @hi-ogawa & @sheremet-va - please propose better name here. 🙏

Internally this feature also uses term extendedContextCoverage. 🙃

I don't think worker really fits in here, both child process and a worker thread is a worker in my opinion, at least that's how we defined it for pools, maybe trackProcessAndThreads is more accurate.

I would vote for something like includeSubprocesses/instrumentSubprocesses - subprocess can refer to anything, not just a fork/thread/service worker

In debugging world there is also --follow-forks mode (in C), in vscode it's autoAttachChildProcesses (although it also follows workers)

How about autoAttachChildContext? Or autoAttachWorkers and imply Worker is processes too. 🤔

I feel like the common denominator here is subprocess, I wouldn't call any subprocess a worker, but every worker a subprocess

It's not a process in a sense of node:child_process, but it is a process in a general sense

No, it's not a process even in a general sense.

Well, process is not a worker in a general sense

Worker is already taken and it would be confusing to reuse the word within the Vitest repository. Subprocess to me sounds like the most general way to describe anything spawned by the user code

Worker is not a term that's used in general sense 🙃. But sure let's think in NodeJS context.

Ok, let's use autoAttachSubprocess. I don't care that much.

…eads` contexts

sheremet-va · 2026-04-27T12:10:55Z

Awesome!

AriPerkkio commented Mar 26, 2026

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Comment thread packages/coverage-v8/src/intercept-new-run-context.ts Outdated

AriPerkkio force-pushed the feat/coverage-process-thread-context branch from 88a5c08 to fa35cd5 Compare March 26, 2026 13:49

AriPerkkio added the cr-tracked label Mar 26, 2026

AriPerkkio force-pushed the feat/coverage-process-thread-context branch 3 times, most recently from fef5aec to 188a95f Compare March 31, 2026 18:35

AriPerkkio force-pushed the feat/coverage-process-thread-context branch 2 times, most recently from 70f7641 to 3d1dce2 Compare April 6, 2026 14:03

AriPerkkio commented Apr 6, 2026

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Comment thread test/coverage-test/test/extended-run-context.v8.test.ts Outdated

AriPerkkio force-pushed the feat/coverage-process-thread-context branch 3 times, most recently from ed25468 to 66e52a1 Compare April 6, 2026 19:31

AriPerkkio commented Apr 7, 2026

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Comment thread packages/coverage-v8/src/index.ts Outdated

AriPerkkio force-pushed the feat/coverage-process-thread-context branch 3 times, most recently from fb7116a to c0a7985 Compare April 12, 2026 09:55

AriPerkkio commented Apr 12, 2026

View reviewed changes

AriPerkkio force-pushed the feat/coverage-process-thread-context branch 3 times, most recently from b97e821 to 63acca7 Compare April 13, 2026 09:31

This was referenced Apr 13, 2026

coverage not collected from sub-propcesses result from child_process APIs #7064

Closed

@vitest/web-worker error when using browser environment #4899

Open

AriPerkkio marked this pull request as ready for review April 13, 2026 10:52

AriPerkkio force-pushed the feat/coverage-process-thread-context branch from 63acca7 to 92ab430 Compare April 13, 2026 10:55

AriPerkkio commented Apr 13, 2026

View reviewed changes

AriPerkkio requested review from hi-ogawa and sheremet-va and removed request for sheremet-va April 13, 2026 10:57

AriPerkkio requested a review from sheremet-va April 13, 2026 10:57

AriPerkkio mentioned this pull request Apr 14, 2026

Add E2E code coverage storybookjs/mcp#156

Draft

AriPerkkio force-pushed the feat/coverage-process-thread-context branch from 92ab430 to c1073e1 Compare April 20, 2026 10:05

AriPerkkio added 2 commits April 21, 2026 08:42

feat(coverage): v8 to track node:child_process and `node:worker_thr…

9832a38

…eads` contexts

fix: rename trackProcessAndWorker to autoAttachWorkers

2eb5e8d

AriPerkkio force-pushed the feat/coverage-process-thread-context branch from c1073e1 to 2eb5e8d Compare April 21, 2026 05:47

AriPerkkio commented Apr 22, 2026

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Comment thread docs/config/coverage.md Outdated

docs: remove experimental status

2e65953

hi-ogawa reviewed Apr 22, 2026

View reviewed changes

Comment thread packages/coverage-v8/src/index.ts

Comment thread packages/coverage-v8/src/index.ts

AriPerkkio added 2 commits April 24, 2026 10:08

fix: don't crash when no child contexts are spawned

1573a6b

fix: generated new NODE_V8_COVERAGE between each isolate: false runs

9a0063c

AriPerkkio requested a review from hi-ogawa April 24, 2026 07:15

AriPerkkio added 2 commits April 24, 2026 16:00

fix: rename autoAttachWorkers to autoAttachSubprocess

ffe6ed9

fix: prevent reading same results twice when isolate: false

cc332ea

hi-ogawa approved these changes Apr 27, 2026

View reviewed changes

sheremet-va approved these changes Apr 27, 2026

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sheremet-va merged commit 9baa5fa into vitest-dev:main Apr 27, 2026
16 of 17 checks passed

AriPerkkio deleted the feat/coverage-process-thread-context branch April 27, 2026 12:12


		Collect coverage only for files changed since a specified commit or branch. When set to `true`, it uses staged and unstaged changes.

		## coverage.trackProcessAndWorker

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Description

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sheremet-va commented Apr 27, 2026

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AriPerkkio commented Mar 26, 2026 •

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