proptest VS go-fuzz

In this post, I will tell you how I used property testing with the Proptest library in Rust to ensure the correctness of a bunch of generated serialization/deserialization code for the Apache Kafka protocol.

proptest: Property-based testing with random input generation.

Isn't proptest something that could handle this?

https://github.com/proptest-rs/proptest

Proptest is a Rust crate for property-based testing. Recently I wanted/needed to manually implement a proptest strategy for my own type, and I realized that there is not that much material on how to do it. So I wrote a post where I tried to describe what I learned. It's a bit niche, but I hope that someone at some point will find it useful.

Take a look at proptest.

Yes exactly, you can also add to this fuzzing and property based testing.

proptest is great! It generates random input data according to some rules, and if the input fails it saves random seed into a file so that failing inputs are guaranteed to be tested on the subsequent runs (as well as new random inputs). It also doesn't immediately stop on fail but tries to find a minimal failing input first.

The only other crate I could find is proptest, but it looks a lot more complicated, and I don't know if lets you skip the shrinking step as quickcheck does. I've been reading the book and going through the docs, but a quick answer would be appreciated.

We just released proptest 1.1.0, a property-testing framework for Rust. Proptest has recently found new maintainers, and this marks the first new release of proptest in ~2 years.

Hi, I'm working on a fuzzer, that fuzzes APIs based on OpenAPI specification. I'd like to implement shrinking. It means that when an interesting input (for the API) is found, I'd like to create the smallest possible input that still causes the same behaviour of the API. I'd like to implement a payload generation via proptest, because it already has the shrinking ability. I'm having issues implementing the JSON object as a proptest strategy. Here is what I tried so far. I explained it in a detail in stackoverflow question but it did not reach many people. Thanks for your help!

I used this method successfully for my qjson package . It accepts as input a human readable json. It detected a condition I forgot to check in a few minutes. I used the go fuzzer go-fuzz from Dmitry Vyukov. Check the impressive list of trophies at the end of the README. These are bugs found by the fuzzer.

It does instrumented fuzzing. The older https://github.com/dvyukov/go-fuzz would rewrite your sources to inject the instrumentation and pass the rewritten sources to the compiler, but it didn't really work with Go modules. This is something that probably makes sense to integrate with the compiler toolchain, same as `go test`'s coverage testing.

And another Go-Fuzz

Anyone seen good articles on converting go-fuzz tests to native fuzzing? Specifics on the new corpus format and a converter from go-fuzz would be really useful.

It’s great to hear that the fuzzer is built on go-fuzz so hopefully the conversion process won’t be too bad: https://github.com/dvyukov/go-fuzz/issues/329

> it shows the limitations of the language that you can't just build this inside the language.

Not sure why you'd make that assumption. https://github.com/dvyukov/go-fuzz

Rather than explore the specific issues my tests found, I started playing with running https://github.com/dvyukov/go-fuzz against go-json which seems to have fairly quickly found some issues. I've opened https://github.com/goccy/go-json/issues/174 to start the conversation about how you want to proceed here.

You can check the go-fuzz's trophies here.

Maybe you can add support for using a fuzzer like https://github.com/dvyukov/go-fuzz or https://github.com/google/gofuzz

I recently stumbled upon go-fuzz (that is also linked in the proposal). I'm amazed how fuzzing has made the go toolchain stronger and integrated this technique into some of our CI/CD pipelines for continuous testing. Having native fuzzy testing support (not just in go) would be great.

Go tests and benchmarks are so easy to write and run: just add TestFoo and BenchmarkFoo functions to a bar_test.go file, and "go test" does the rest. It's currently doable, but it requires a 3rd party library (go-fuzz) and a bit of fluffing around. This will make fuzz testing an equally first-class citizen with standard Go tooling (just add FuzzFoo), and as such we'll probably see a lot more people testing with fuzzing.

I used go-fuzz in GoAWK and it found several bugs (see https://benhoyt.com/writings/goawk/#fuzz-testing), and almost everyone who's done fuzz testing has similar reports. Certainly go-fuzz has found many, many bugs in Go itself: https://github.com/dvyukov/go-fuzz#trophies

For what it's worth, I wrote an article for LWN about the upcoming support for built-in fuzzing in Go: https://lwn.net/Articles/829242/ (of course, if you want full details, read the full proposal).