fast-check VS Vale

Libraries like JSVerify or Fast-Check offer essential tools to facilitate property-based testing.

Strong agree!

For JavaScript, I suggest folks check out fast-check [0] and this introduction to property-based testing that uses fast-check [1].

This is broadly useful, but one specific place I've found it helpful was to check redux reducers against generated lists of actions to find unchecked edge cases and data assumptions.

[0] https://github.com/dubzzz/fast-check

Brilliant, this is a massive improvement. Previously I was fumbling around in https://github.com/dubzzz/fast-check/tree/main/packages/fast-check/documentation for info.

There's a library for exactly that: FastCheck.

It makes @fast-check/jest, the best option to integrate Jest and fast-check, as it provides an abstraction over both to ease their mutual integration.

The closest that I know of (and I have not used this) is zod-fast-check. It generates fast-check “arbitraries” (test data generators) for property-based testing based on zod schemas. Of course, this requires that you use zod to define your types, which has some downsides. Fortunately there is another tool, ts-to-zod, (which I also have not used) which will codegen zod schemas based on TS type definitions. If you thread these four libraries together you should end up with the ability to write random tests on generated data with very little overhead. In theory.

For something like this, I might break out fast-check for testing. It’s good at generating a wide range of values for a given type, and could help you get good test coverage without having to hand-author a lot of repetitive error inputs.

Not to be confused with Vale[0].

[0] https://vale.dev/

The article says they created a deterministic hypervisor that runs all pseudorandom behavior from a starting seed to enable perfect re-playability.

But that's all we know so far. I'm assuming there'll be some sort of fuzz testing, and static analysis or some defining actions that your software can perform.

Honestly it sounds a lot like it has a lot of crossover with what the Vale language is trying to solve: https://vale.dev/, but focused on trying to get existing software to that state instead of creating a new language to make new software already be at that state by default.

Why go through all the trouble when you can do this: https://www.hylo-lang.org/ and not spend a second thinking of lifetimes? No, copies will not be issued unless necessary.

Or why not keep exploring this idea as well? More research-oriented than the first one right now, though, so take it with a grain of salt: https://vale.dev/

Another relevant language might be Vale (https://vale.dev), which is aiming for "perfect replayability": https://verdagon.dev/blog/perfect-replayability-prototyped

Interesting. Very low level though and C(++) centric. She there any thoughts on combining the hardware and OS features with rust or https://vale.dev ?

Use a runtime memory management solution that's cheaper than garbage collection (see Vale)

This seems like a tool I'll be using, and this is an almost meaningless criticism, but why the name?

There's already the Vale programming language (https://vale.dev/), but moreover, I don't get the meaning of "vale". You could call it something like Englint which actually hints its purpose.