Quickcheck in Go?

[Aaron Schlesinger]

Hi Everyone - 

I'm trying to build a QuickCheck / ScalaCheck like library for Go. I think property based testing would be especially valuable for many of the systems level programs being built in Go, and I also just find it fun to implement.

My problem so far is that I have to use interface{} everywhere (I aliased it to Any if you're reading the code.) For example, I built a Generator interface that generates interface{} types. I know and accept that Go doesn't have generics (and I did before I started building this thing) and I'm not asking for the feature here. Instead, I'm asking a few more specific (and I hope more constructive) questions:

1. how can I make the Generator implementations better indicate what type they will generate?
2. each LazyList will be homogeneous in its type. is there a better way to indicate that fact?
1. if so, is there a good way to indicate its type?
3. how (if at all) will go generate help with (1) or (2)?

[Aaron Schlesinger]

... and I forgot the link to my repo: github.com/arschles/gocheck

[Henrik Johansson]

What is not enough in the one supplied with Go?

http://golang.org/pkg/testing/quick/

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[Aaron Schlesinger]

A few limitations that I see:

1. It doesn't support the semantic concept of a property and, as a result, property composition.
   
2. Similar to (1) it doesn't support the generator concept or generator composition. I think this and (1) are important for testing larger systems composed of larger data structures.
3. The library doesn't seem to do shrinking. does anyone know for sure?

That all being said, I have plans to see if I can use testing/quick under the hood for generators.

[Dmitry Vyukov]

It would also be awesome to use the new testing.Coverage function to
do guided fuzzing:
http://tip.golang.org/pkg/testing/#Coverage

[Aaron Schlesinger]

+1. anything that gets to the "answer" (proving the property wrong) faster

for now, I'm more concerned with figuring out a better way to make the API clear to people writing tests

[Caleb Spare]

Be aware that 'gocheck' is the name of one of the earliest and most
popular third-party testing packages for Go.

http://labix.org/gocheck

[Aaron Schlesinger]

Yup, I'm aware. Thanks!

[bodo.j...@leanovate.de]

I stumbled upon this myself and "testing/quick" was just not sophisticated enough.

So I started to port ScalaCheck myself: https://github.com/leanovate/gopter

There are still some loose ends but overall its already working.

Any feedback would be highly welcomed.