Nico Jansen@_nicojs

🀝 Open source advocate πŸ‘½ Maintainer of @stryker_mutator πŸ’Ό Manager and trainer @InfoSupportBV πŸ’š Loves green energy and vegetables

 Holland and Belgium
github.com/nicojs
Joined January 2012
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OK, time for some nerdy #mutationtesting internals tweets πŸ€“. @stryker_mutator uses mutation switching (or "mutant schemata"). All mutants are placed in the code at the same time, yet a single mutant is active at any one time. What does this mean for StrykerJS?πŸ€”
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When StrykerJS places these 2 mutants, it looks like: const even = global.activeMutant === "1"? numbers.map(n => global.activeMutant === "2"? n / 2 : n % 2) : numbers?.map(n => global.activeMutant === "2"? n / 2 : n % 2) Whoaaaahh 😱 What happened here?
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It appears that StrykerJS placed the second mutant twice 😲. That looks scary, but it is still correct from a Mutation Switching point of view: only one can be active at the same time. However, we want to see each mutant exactly once. It is most definitely a bug in StrykerJS.
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Stryker4s, the #mutationtesting tool for @scala_lang, is now a lot faster πŸš€. We've achieved a ~60x performance improvement 🀯! Read up on how we did it and how to use it today! stryker-mutator.io/blog/stry…

Stryker4s: from 40 minutes to 40 seconds | Stryker Mutator

Stryker4s is your friendly mutation testing framework for Scala. Compared to earlier versions, Stryker4s 0.12 achieves a 60x speed increase in some scenarios 🀯. Are you curious to know how? Keep on...

stryker-mutator.io
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Q: Should open source developers start requiring people to use Linux, Mac (or WSL) to develop their projects? And stop focussing on Windows?
33% Yes
67% No
6 votes β€’ Final results
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The reason I'm asking is that supporting Windows is actually a big productivity drain. I'm quite used to seeing these kind of CI pipelines
Me 🀠: "What the use case is for 'call by value' in @scala_lang ." @Hugo_vrijswijk πŸ¦Έβ€β™‚οΈ: "Well, if you would want to implement your own `or`-operator...". 🀠: "Implementing your own `or` operator is the most Scala-ish thing I've ever heard!"
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Damn you @buildsghost! πŸ˜‰ Enjoy this song, everyone!
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StrykerJS 5.0 is here πŸš€ With a new πŸ§ͺtest view in your reports telling you which tests are 'useless'. Also: new mutators, support for `--ignorePatterns`, `perTest` coverage analysis by default, and more! Read up on what's new and get it today! πŸ‘½πŸ”« stryker-mutator.io/blog/anno…
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Nico Jansen retweeted
Elon Musk
@elonmusk
13 May 2021
It is high time there was a carbon tax!
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Took a bit longer than others, but I finished reading the latest edition of the @JavaMagazineNL! Three articles about @ASFMavenProject and (myself excluded) three @InfoSupportBV colleagues as authors! Really enjoyed it.
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🀫 StrykerJS v5 will be able to tell you which tests are useful and which aren't github.com/stryker-mutator/s…
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Look what I found in my mailbox today! A brand new @JavaMagazineNL, featuring a brand new article by @MartinKanters and yours truly. Subject: brand new features in the next major release of @ASFMavenProject. Stay tuned! #opensource #awesomesauce
Picture of article in paper magazine about Maven 4

ALT Picture of article in paper magazine about Maven 4

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Watch my latest @YouTube video about Mutation Testing #mutationtesting #coding #testautomation youtu.be/41ywot_Z_Ts
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All I wanted for my birthday is to drop node 10 support in StrykerJS @stryker_mutator . Thanks for delivering, @nodejs ! πŸ₯³
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Don't you just love developing important features? πŸ˜πŸ¦Έβ€β™€οΈπŸ€˜
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πŸŽ‰ I just got my first PR accepted for Jest πŸƒ. Yes, it will help improve Jest support in StrykerJS πŸ‘½. Thanks to @SBekkhus for all the help 🀟 github.com/facebook/jest/pul… @fbjest
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