Yes, for a long while – I believe it's fairly widely used (and it's absolutely excellent!)
merqurio•Jul 9, 2026
Happy user here !
DennisL123•Jul 9, 2026
Yes, been using it for 18’ish months. Works great.
aabhay•Jul 9, 2026
Yep. Tokio uses it for their tests in CI as well last I checked.
musicmatze•Jul 9, 2026
Been using it for years, for opensource stuff and at work. No issues whatsoever.
gdcbe•Jul 9, 2026
Yes we use it for rama [1]. You can check its justfile and CI workflow file how we use it. Those run thousands and thousands of tests thx to nextest and what feels like instantly (once compiled).
Large projects build with rama use it as well. But those are proprietary from partners so sadly cannot share those.
I somehow tried to make sense of the name as a superlative form of "next". Perhaps next-test would have been fine?
sunshowers•Jul 9, 2026
That is indeed the pun =)
patates•Jul 9, 2026
Oh, sorry then, thanks for the clarification :)
mightyham•Jul 9, 2026
Coming from the DC area, this comment reminds me of how the metro payment system "Smartrip" was recently renamed to "Smart Trip".
sunshowers•Jul 9, 2026
Thanks for posting about this! I'm the main author of nextest, and it represents my best foot forward for how Rust testing should be done. Happy to answer questions though I might be a bit intermittent.
landr0id•Jul 9, 2026
Big fan of nextest and this is my first time seeing this site. I'll be real I feel a bit ridiculous commenting this but you might want to consider rephrasing this:
>Treat tests as cattle, not pets. Detect and terminate slow tests.
Not sure saying, "hey, treat your tests as an animal you can kill at will" paints the right image.
sunshowers•Jul 9, 2026
That's fair! I'll find a way to rephrase it.
edit: Updated to "Detect and handle slow tests". Thanks again!
trollbridge•Jul 9, 2026
This is from the Kubernetes saying of "treat servers like cattle, not pets". Of course, some people like me keep cattle as pets, but then again I also name my servers, even the virtual or containerised ones.
sunshowers•Jul 9, 2026
Yeah that was indeed the inspiration (though I'm pretty sure it predates Kubernetes!) but the juxtaposition with "terminate" is unfortunate.
wojciii•Jul 9, 2026
I liked the way it was phrased. You can't make everybody happy. :)
seanhunter•Jul 9, 2026
It’s a horrible saying in that context also.
embedding-shape•Jul 9, 2026
I mean, I like animals too, but in context it does make sense. The context was to treat them as "obtainable yet ultimately killable entities you keep as a group, not individuals", which cattle pretty much is. Unless you consider keeping cattle as draft animals, but I think that stopped being the main purpose a long time ago.
It got the point across, at a time where most people basically acquired servers, kept them until they died, and he was trying to push a development workflow where you constantly close("kill")/bring up new servers.
entrope•Jul 9, 2026
IMO, "make your servers fungible" is a better way to express the intent: slightly shorter, no metaphors, although "fungible" is a less common word. Maybe that's just me. (Edited to add: "make your tests fungible" has I think the wrong connotation; I think the original wording on the blog is about test executions -- and "make your test executions fungible" does seem like a good goal, similar to ACID guarantees for database transactions.)
embedding-shape•Jul 9, 2026
Before that, I used to call them "ephemeral", and of course half the people asked what "ephemeral" means, probably "fungible" would be met with similar question, unless the crowd is cryptocurrency-adjacent, that term seems understood there.
jen20•Jul 9, 2026
That (unpleasant) saying predates Kubernetes by at least half a decade.
mhluongo•Jul 9, 2026
It resonated with me!
Zababa•Jul 9, 2026
Fungible/non fungible is a good alternative, and maybe the technically correct word. But I think in that case it doesn't apply and the change the author did is better.
27183•Jul 9, 2026
"Treat tests as annuals not perennials"
"Treat tests as workers not management"
mrec•Jul 9, 2026
Have there been any discussions about upstreaming this into cargo proper? Are there any significant downsides to nextest compared to its predecessor?
sunshowers•Jul 9, 2026
The How it works [1] and Why process-per-test? [2] pages should answer your questions.
Ah, I see. You're aiming to become the hashbrown of testing.
sunshowers•Jul 9, 2026
Oh gosh, were we to be so lucky :) just aiming to solve problems my coworkers and users see, and doing it with care, is all.
gdcbe•Jul 9, 2026
Thank you very much for developing nextest. It is what allows our projects like rama [1] to run thousands and thousands of tests in a blink of an eye! Keep it up!
Hey, I love nextest. But, perhaps because of the one-process per test approach, endpoint security solutions like CrowdStrike Falcon or Palo Alto Cortex tend to make computers hang whenever tests kick-in. I would love if you were able to introduce a workaround, because none of those companies will fix their stuff. I am guessing a possible mitigation would be to have stagger the first invocation of any large test binary, but I haven't had a chance to dig deep into this issue.
arw0n•Jul 9, 2026
Wouldn't running the tests in a container solve that issue? Or is that another thing that gets flagged?
sunshowers•Jul 9, 2026
Nextest does run tests in lexicographic (binary, test name) order by default, so first executions tend to be staggered. Unfortunately this is a known problem that is much larger than nextest, and it is why Windows introduced Dev Drive with a mode to disable AV/EDR on those drives entirely.
I wish I had a better answer here — it is frustrating how poorly behaved the EDR stuff tends to be. Maybe I should try and network a bit to get in touch with the people working on this stuff. (Planning to be at DEF CON this year, so come find me if you work on this stuff and will be there!)
cogman10•Jul 9, 2026
First, I like how all this works, it's great.
Can you run tests serially in the (horrible) case when tests need to build on one another?
How are you querying for the tests? Is that just built into rust's test stuff?
Would it be possible to fork the test process? It'd be pretty interesting if you could spawn a test process, and then fork it for each test to save both on memory and any static state stored within the test.
sunshowers•Jul 9, 2026
> Can you run tests serially in the (horrible) case when tests need to build on one another?
> How are you querying for the tests? Is that just built into rust's test stuff?
Just running --list against test binaries.
> Would it be possible to fork the test process? It'd be pretty interesting if you could spawn a test process, and then fork it for each test to save both on memory and any static state stored within the test.
This is possible in principle, but nextest doesn't really inject itself into tests like that (injection can cause reliability issues in practice, and a big focus of nextest is reliability). Forking is also not possible in multithreaded programs.
dpc_01234•Jul 9, 2026
Thank you! It's great.
satvikpendem•Jul 9, 2026
I love nextest, it's been great. This along with bacon catches a lot of issues.
weinzierl•Jul 9, 2026
The "execution model" page[1] is documentation at its best!
It answered 90% of the questions I had at the monent. Thank you!
watch it running 32.5k unit tests without breaking a sweat!
sunshowers•Jul 9, 2026
Thanks! BTW you might enjoy setting CARGO_TERM_COLOR=always in your environment :) dtolnay/rust-toolchain does this automatically but it looks like you aren't using that action.
mohsen1•Jul 9, 2026
Thanks! Any pro tips for sharding? I landed on single job because couldn't get cache to work properly for shards to be fast enough to worth it
sunshowers•Jul 9, 2026
I think in practice you're right that GitHub Actions' caching slowness can end up dominating performance. I don't have any great tips other than to measure.
evntdrvn•Jul 9, 2026
I've basically abandoned GA's caching for most things because measurements ended up showing things were slower with caching than without :woozy:
jstrong•Jul 9, 2026
seems like `cargo nextest run` just runs `--lib` tests by default? however, `cargo test` is not so slow if you do `cargo test --lib`. how do I get nextest to execute the doc tests, too?
The benchmarks are against non-doctest cargo test runs. (But you should measure against your own project, of course!) Unfortunately Cargo doesn't provide enough information for nextest to run doctests reliably with.
jtwaleson•Jul 9, 2026
Super happy user here! It's an excellent piece of engineering.
We're running a fork that supports a "sidecar" server for running multiple integration tests against. So if any tests that need the server are included, it spawns the server, runs the integration tests, and then shuts it down. By re-using the same server we speed up our runs tremendously.
8 Comments
edit: Thanks, will try!
Large projects build with rama use it as well. But those are proprietary from partners so sadly cannot share those.
[1]: https://github.com/plabayo/rama
>Treat tests as cattle, not pets. Detect and terminate slow tests.
Not sure saying, "hey, treat your tests as an animal you can kill at will" paints the right image.
edit: Updated to "Detect and handle slow tests". Thanks again!
It got the point across, at a time where most people basically acquired servers, kept them until they died, and he was trying to push a development workflow where you constantly close("kill")/bring up new servers.
"Treat tests as workers not management"
[1] https://nexte.st/docs/design/how-it-works/
[2] https://nexte.st/docs/design/why-process-per-test/
[1] https://ramaproxy.org
I wish I had a better answer here — it is frustrating how poorly behaved the EDR stuff tends to be. Maybe I should try and network a bit to get in touch with the people working on this stuff. (Planning to be at DEF CON this year, so come find me if you work on this stuff and will be there!)
Can you run tests serially in the (horrible) case when tests need to build on one another?
How are you querying for the tests? Is that just built into rust's test stuff?
Would it be possible to fork the test process? It'd be pretty interesting if you could spawn a test process, and then fork it for each test to save both on memory and any static state stored within the test.
Yes: https://nexte.st/docs/configuration/test-groups/ (edit: though tests that build on each other is a bit harder — test groups are meant for when tests need access to a shared resource)
> How are you querying for the tests? Is that just built into rust's test stuff?
Just running --list against test binaries.
> Would it be possible to fork the test process? It'd be pretty interesting if you could spawn a test process, and then fork it for each test to save both on memory and any static state stored within the test.
This is possible in principle, but nextest doesn't really inject itself into tests like that (injection can cause reliability issues in practice, and a big focus of nextest is reliability). Forking is also not possible in multithreaded programs.
It answered 90% of the questions I had at the monent. Thank you!
[1] https://nexte.st/docs/design/how-it-works/
https://github.com/tsz-org/tsz/actions/runs/29002057457/job/...
watch it running 32.5k unit tests without breaking a sweat!
We're running a fork that supports a "sidecar" server for running multiple integration tests against. So if any tests that need the server are included, it spawns the server, runs the integration tests, and then shuts it down. By re-using the same server we speed up our runs tremendously.
Discussion thread on gh: https://github.com/nextest-rs/nextest/discussions/3330