Nicolas Dubien
@nicolas.dubien.me
Author of @fast-check.dev (🌐 https://fast-check.dev) ∙ Lead Principal Software Engineer @GoPigment ∙ Opinions are my own #Testing #JavaScript #TypeScript #React
Reposted by Nicolas Dubien
Did you know about the `/*@__NO_SIDE_EFFECTS__*/` annotation?
It tells bundlers that a function has no side effects so every call to it can be tree-shaken if the result is unused.
Most bundlers and minifiers support it today.
But there's a nuance most people miss 👇
It tells bundlers that a function has no side effects so every call to it can be tree-shaken if the result is unused.
Most bundlers and minifiers support it today.
But there's a nuance most people miss 👇
February 17, 2026 at 8:29 PM
Did you know about the `/*@__NO_SIDE_EFFECTS__*/` annotation?
It tells bundlers that a function has no side effects so every call to it can be tree-shaken if the result is unused.
Most bundlers and minifiers support it today.
But there's a nuance most people miss 👇
It tells bundlers that a function has no side effects so every call to it can be tree-shaken if the result is unused.
Most bundlers and minifiers support it today.
But there's a nuance most people miss 👇
The worst thing is probably that the diagram is not only wrong but is a copy of a real one... nvie.com/posts/a-succ...
February 16, 2026 at 8:36 PM
The worst thing is probably that the diagram is not only wrong but is a copy of a real one... nvie.com/posts/a-succ...
Reposted by Nicolas Dubien
In the next version of Vitest you can track leaking asynchronous resources via `--detect-async-leaks` option! Available in v4.1.0-beta.4 release. 🔍
(notice missing await in the example)
(notice missing await in the example)
February 16, 2026 at 12:50 PM
In the next version of Vitest you can track leaking asynchronous resources via `--detect-async-leaks` option! Available in v4.1.0-beta.4 release. 🔍
(notice missing await in the example)
(notice missing await in the example)
Reposted by Nicolas Dubien
The "export defer" TC39 proposal aims to introduce a similar optimization *at the language level*, so that you can rely on it in all the tools and environments that you might run your code with.
Just because you need one thing from a module, you shouldn't pay the cost of all the others!
Just because you need one thing from a module, you shouldn't pay the cost of all the others!
February 12, 2026 at 3:45 PM
The "export defer" TC39 proposal aims to introduce a similar optimization *at the language level*, so that you can rely on it in all the tools and environments that you might run your code with.
Just because you need one thing from a module, you shouldn't pay the cost of all the others!
Just because you need one thing from a module, you shouldn't pay the cost of all the others!
Reposted by Nicolas Dubien
This Week In React 268:
⚛️
- Bulletproof Comps
- Render Types
- Tambo
- Logo Soup
- React Compiler
- Exit anims
- React Compiler
- React2AWS
- Ink
📱
- React Native 0.84
- Gesture Handler
- Rozenite
- Storybook
- JSON Render
- Targets
🍿 Read/subscribe: thisweekinreact.com/newsletter/268
⚛️
- Bulletproof Comps
- Render Types
- Tambo
- Logo Soup
- React Compiler
- Exit anims
- React Compiler
- React2AWS
- Ink
📱
- React Native 0.84
- Gesture Handler
- Rozenite
- Storybook
- JSON Render
- Targets
🍿 Read/subscribe: thisweekinreact.com/newsletter/268
February 11, 2026 at 7:55 PM
This Week In React 268:
⚛️
- Bulletproof Comps
- Render Types
- Tambo
- Logo Soup
- React Compiler
- Exit anims
- React Compiler
- React2AWS
- Ink
📱
- React Native 0.84
- Gesture Handler
- Rozenite
- Storybook
- JSON Render
- Targets
🍿 Read/subscribe: thisweekinreact.com/newsletter/268
⚛️
- Bulletproof Comps
- Render Types
- Tambo
- Logo Soup
- React Compiler
- Exit anims
- React Compiler
- React2AWS
- Ink
📱
- React Native 0.84
- Gesture Handler
- Rozenite
- Storybook
- JSON Render
- Targets
🍿 Read/subscribe: thisweekinreact.com/newsletter/268
Reposted by Nicolas Dubien
useEffectEvent makes handling events in Effects much easier and saves unnecessary unmounting and remounting of listeners. It now has awesome new docs: react.dev/reference/re...
Thank you to @ricky.fm the updates, and @danabra.mov and @stephanjnoel.bsky.social for reviewing
Thank you to @ricky.fm the updates, and @danabra.mov and @stephanjnoel.bsky.social for reviewing
useEffectEvent – React
The library for web and native user interfaces
react.dev
February 6, 2026 at 3:44 PM
useEffectEvent makes handling events in Effects much easier and saves unnecessary unmounting and remounting of listeners. It now has awesome new docs: react.dev/reference/re...
Thank you to @ricky.fm the updates, and @danabra.mov and @stephanjnoel.bsky.social for reviewing
Thank you to @ricky.fm the updates, and @danabra.mov and @stephanjnoel.bsky.social for reviewing
Has anyone tricks to review PRs that look to be vibe-coded? I'm always in between:
· if it's vibe-coded without self review let's not lose time with trying to answer with long messages and helping the dev
· otherwise it feels legit to help and suggest other options
· if it's vibe-coded without self review let's not lose time with trying to answer with long messages and helping the dev
· otherwise it feels legit to help and suggest other options
February 6, 2026 at 12:47 PM
Has anyone tricks to review PRs that look to be vibe-coded? I'm always in between:
· if it's vibe-coded without self review let's not lose time with trying to answer with long messages and helping the dev
· otherwise it feels legit to help and suggest other options
· if it's vibe-coded without self review let's not lose time with trying to answer with long messages and helping the dev
· otherwise it feels legit to help and suggest other options
Reposted by Nicolas Dubien
By the way, TypeScript is finally strict by default 🎉
February 5, 2026 at 5:05 PM
By the way, TypeScript is finally strict by default 🎉
Reposted by Nicolas Dubien
@npmx.dev celebrates 1000 issues and PRs within the last 13 days, 22 hours, 18 minutes and 9 seconds.
Celebrate with us in #1000
github.com/npmx-dev/npm...
Celebrate with us in #1000
github.com/npmx-dev/npm...
Celebrating 1000 issues and PRs · Issue #1000 · npmx-dev/npmx.dev
In the last 2 weeks (rounded), the community has submitted 1000 issues + PRs to this repository. Let's celebrate this milestone 🥳 Stats for nerds It has been exactly 13 days, 22 hours, 18 minutes a...
github.com
February 5, 2026 at 8:32 AM
@npmx.dev celebrates 1000 issues and PRs within the last 13 days, 22 hours, 18 minutes and 9 seconds.
Celebrate with us in #1000
github.com/npmx-dev/npm...
Celebrate with us in #1000
github.com/npmx-dev/npm...
Reposted by Nicolas Dubien
Spread love 💕 Like us on @npmx.dev, npmx.dev/package/fast...
npmx
npmx.dev
February 4, 2026 at 12:39 PM
Spread love 💕 Like us on @npmx.dev, npmx.dev/package/fast...
Reposted by Nicolas Dubien
Hey, other companies 👋
@voidzero.dev is giving a good example here. If you need help defining your company's open-source funding strategy, my DMs are open. We need every company to step up its funding game. Let's take care of our maintainers, or the whole ecosystem will collapse.
@voidzero.dev is giving a good example here. If you need help defining your company's open-source funding strategy, my DMs are open. We need every company to step up its funding game. Let's take care of our maintainers, or the whole ecosystem will collapse.
February 2, 2026 at 1:18 PM
Hey, other companies 👋
@voidzero.dev is giving a good example here. If you need help defining your company's open-source funding strategy, my DMs are open. We need every company to step up its funding game. Let's take care of our maintainers, or the whole ecosystem will collapse.
@voidzero.dev is giving a good example here. If you need help defining your company's open-source funding strategy, my DMs are open. We need every company to step up its funding game. Let's take care of our maintainers, or the whole ecosystem will collapse.
Reposted by Nicolas Dubien
🚀 Lazy Barrel Optimization in Rolldown
Barrel files, files that re-export from other modules, are common in modern JavaScript projects but a nightmare for your build time.
Rolldown now has Lazy Barrel Optimization to fix this.
Here's how it works 🧵
Barrel files, files that re-export from other modules, are common in modern JavaScript projects but a nightmare for your build time.
Rolldown now has Lazy Barrel Optimization to fix this.
Here's how it works 🧵
February 3, 2026 at 4:40 PM
🚀 Lazy Barrel Optimization in Rolldown
Barrel files, files that re-export from other modules, are common in modern JavaScript projects but a nightmare for your build time.
Rolldown now has Lazy Barrel Optimization to fix this.
Here's how it works 🧵
Barrel files, files that re-export from other modules, are common in modern JavaScript projects but a nightmare for your build time.
Rolldown now has Lazy Barrel Optimization to fix this.
Here's how it works 🧵
Reposted by Nicolas Dubien
The next @vitest.dev version has a new `test.extend` syntax that supports type inference (including the correct scope)!
main.vitest.dev/guide/test-c...
main.vitest.dev/guide/test-c...
February 2, 2026 at 4:57 PM
The next @vitest.dev version has a new `test.extend` syntax that supports type inference (including the correct scope)!
main.vitest.dev/guide/test-c...
main.vitest.dev/guide/test-c...
Am I the only one or is Claude Code from @anthropic.com automatically setting up @fast-check.dev along @vitest.dev when asked to add tests to a project?
The prompt was:
> add test coverage to this repository, feel free to add the packages you feel relevant to achieve that task
No skill added
The prompt was:
> add test coverage to this repository, feel free to add the packages you feel relevant to achieve that task
No skill added
February 2, 2026 at 11:22 AM
Am I the only one or is Claude Code from @anthropic.com automatically setting up @fast-check.dev along @vitest.dev when asked to add tests to a project?
The prompt was:
> add test coverage to this repository, feel free to add the packages you feel relevant to achieve that task
No skill added
The prompt was:
> add test coverage to this repository, feel free to add the packages you feel relevant to achieve that task
No skill added
@npmx.dev would it be acceptable to add some property based tests using @fast-check.dev in the repository? I've seen tests on parsing that may benefit from it to detect edge-cases...
Just need to find time to work on them 😬
Just need to find time to work on them 😬
February 1, 2026 at 10:23 AM
@npmx.dev would it be acceptable to add some property based tests using @fast-check.dev in the repository? I've seen tests on parsing that may benefit from it to detect edge-cases...
Just need to find time to work on them 😬
Just need to find time to work on them 😬
Reposted by Nicolas Dubien
👉 Our testing expert is there: skills.sh/dubzzz/fast-...
We will restrict the scope to non-e2e but plan to cover testing-library and playwright.
🙏 Help welcomed ♥️
Share the word and feel free to contribute, the more contributors the better the rules
We will restrict the scope to non-e2e but plan to cover testing-library and playwright.
🙏 Help welcomed ♥️
Share the word and feel free to contribute, the more contributors the better the rules
February 1, 2026 at 10:13 AM
👉 Our testing expert is there: skills.sh/dubzzz/fast-...
We will restrict the scope to non-e2e but plan to cover testing-library and playwright.
🙏 Help welcomed ♥️
Share the word and feel free to contribute, the more contributors the better the rules
We will restrict the scope to non-e2e but plan to cover testing-library and playwright.
🙏 Help welcomed ♥️
Share the word and feel free to contribute, the more contributors the better the rules
Once we have our first iteration ready, we may ask a few testing folks for their inputs. There are so many ways to test in JavaScript as it can do the front but also the back, running in node but also browsers, deal with other languages (markup, css)...
🧙♂️ We are currently writing down some AI skills for testing in general and some for fast-check itself
Hope it could lead to better tests and less bugs 👾
Hope it could lead to better tests and less bugs 👾
January 31, 2026 at 4:44 PM
Once we have our first iteration ready, we may ask a few testing folks for their inputs. There are so many ways to test in JavaScript as it can do the front but also the back, running in node but also browsers, deal with other languages (markup, css)...
Such great news 🎉
TypeScript excitement 😉
Congrats to @jakebailey.dev on updating upstream tsc to default to an unpinned *latest* yearly edition of ES20xx. Heading for TS 6.0 🎉
This mean less transpilation of new JS features & more use of native language features provided by JS engines 👍
github.com/microsoft/Ty...
Congrats to @jakebailey.dev on updating upstream tsc to default to an unpinned *latest* yearly edition of ES20xx. Heading for TS 6.0 🎉
This mean less transpilation of new JS features & more use of native language features provided by JS engines 👍
github.com/microsoft/Ty...
January 31, 2026 at 4:27 PM
Such great news 🎉
mockReset in @vitest.dev config is amazing! 🚀
At work, it saved us many lines of code and protected us against many wrongly written tests.
At work, it saved us many lines of code and protected us against many wrongly written tests.
January 29, 2026 at 2:48 PM
mockReset in @vitest.dev config is amazing! 🚀
At work, it saved us many lines of code and protected us against many wrongly written tests.
At work, it saved us many lines of code and protected us against many wrongly written tests.
🎙️ So glad to be part of the line up of React Paris 2026
🚀 @nicolas.dubien.me is speaking at #ReactParis 2026
Nicolas reveals how his company built automated systems to catch #performance regressions early; using unit/E2E tests to track re-renders, memory leaks, and costly ops before they hit production.
Learn more & join us in #Paris 👉🏼 react.paris
Nicolas reveals how his company built automated systems to catch #performance regressions early; using unit/E2E tests to track re-renders, memory leaks, and costly ops before they hit production.
Learn more & join us in #Paris 👉🏼 react.paris
January 28, 2026 at 7:59 PM
🎙️ So glad to be part of the line up of React Paris 2026
😱 Jest might block me from going to require(esm) in @fast-check.dev. It seems that one cannot require(esm) in Jest even against recent releases of Node.
Jest being one of our key users, I'm a bit puzzled on the idea of making them unable to move to next major of fast-check or not...
Jest being one of our key users, I'm a bit puzzled on the idea of making them unable to move to next major of fast-check or not...
January 27, 2026 at 10:04 PM
😱 Jest might block me from going to require(esm) in @fast-check.dev. It seems that one cannot require(esm) in Jest even against recent releases of Node.
Jest being one of our key users, I'm a bit puzzled on the idea of making them unable to move to next major of fast-check or not...
Jest being one of our key users, I'm a bit puzzled on the idea of making them unable to move to next major of fast-check or not...
Reposted by Nicolas Dubien
New article: AI-generated tests as ceremony. blog.ploeh.dk/2026/01/26/a...
AI-generated tests as ceremony
On epistemological soundness of using LLMs to generate automated tests.
blog.ploeh.dk
January 26, 2026 at 9:15 AM
New article: AI-generated tests as ceremony. blog.ploeh.dk/2026/01/26/a...
Reposted by Nicolas Dubien
curl maintainer @daniel.haxx.se said the project is shutting down its bug bounty program after maintainers were buried under low-quality, AI-generated slop reports. Security disclosure systems that assume unlimited #OSS maintainer labor are reaching their limits.
socket.dev/blog/curl-sh...
socket.dev/blog/curl-sh...
curl Shuts Down Bug Bounty Program After Flood of AI Slop Re...
A surge of AI-generated vulnerability reports has pushed open source maintainers to rethink bug bounties and tighten security disclosure processes.
socket.dev
January 23, 2026 at 11:15 PM
curl maintainer @daniel.haxx.se said the project is shutting down its bug bounty program after maintainers were buried under low-quality, AI-generated slop reports. Security disclosure systems that assume unlimited #OSS maintainer labor are reaching their limits.
socket.dev/blog/curl-sh...
socket.dev/blog/curl-sh...
copy and paste the bunny and then put something else in his hand
(\_/)
(°-°)
/>❤️>
(\_/)
(°-°)
/>❤️>
copy and paste the bunny and then put something else in his hand
(\_/)
(°-°)
/>🧉>
(\_/)
(°-°)
/>🧉>
January 23, 2026 at 7:53 AM
copy and paste the bunny and then put something else in his hand
(\_/)
(°-°)
/>❤️>
(\_/)
(°-°)
/>❤️>