Adding PropertyAttribute for XUnit

[dharmaturtle]

Inspired by FsCheck's PropertyAttribute, I implemented one for Hedgehog. It currently uses GenX.auto to generate data for methods with the [<Property>] attribute, then checks the method via Property.check.

Currently a draft, but everything works. Next, I'm going to add a way to inject a custom AutoGenConfig. I'll likely copy/paste what FsCheck does.

Related prior discussion: hedgehogqa/fsharp-hedgehog#144

[moodmosaic]

Great work 👍

• Perhaps we can have this as Hedgehog.Xunit instead?
  • The long term goal is to merge (some stuff, or most of the stuff) from Hedgehog.Experimental into Hedgehog (Merge stuff from Hedgehog.Experimental? fsharp-hedgehog#182).
• Are you planning to support Xunit 1.9.2 and/or Xunit 2.*?

[cmeeren]

Personally I'm not interested in this feature; firstly, I find Expecto much more compelling than XUnit; secondly, I like the explicitness of "vanilla" Hedgehog; and thirdly, I have very limited resources for further OSS project support. And as @moodmosaic says, I'm not sure this belongs in the Hedgehog.Experimental repo. Perhaps this could be a separate repo under the hedgehogqa organization?

[moodmosaic]

Perhaps this could be a separate repo under the hedgehogqa organization?

Eventually it could be. If it's of high quality and popular at the same time (e.g. haskell-hedgehog-classes started under chessai's own github and later on we moved it inside the org).

[cmeeren]

Sure. The point being, perhaps this belongs in a separate repo (not just package) and not in Hedgehog.Experimental.

[dharmaturtle]

Hedgehog.Xunit sounds good to me. I'll likely only support Xunit 2.* (and 3.0, when it arrives) as that's what I'm using.

My preferred test runner (NCrunch) doesn't support Expecto, so I'm sticking with Xunit for now.

I'll close this as I agree it doesn't belong in Experimental. I'll leave it in my own github, as it's being built primarily for myself anyway, and we can leave the possibility of it joining the hedgehogqa org ambiguous.

[TysonMN]

From Expecto's README

Expecto also provides a simple API for property based testing using FsCheck.

We want people to use Hedgehog instead! ;)

[moodmosaic]

Yep, basically we'd need both.

[TysonMN]

Can you elaborate on that? Are you saying that there is something about QuickCheck/FsCheck that his technically superior to Hedgehog?

[moodmosaic]

I apologize if I wasn't clear. I meant it's nice to have both Hedgehog.Xunit and Hedgehog.Expecto.

Both would rely on Hedgehog.Experimental.GenX.auto out of the box, with the option to override custom types.

[TysonMN]

The code in this PR is available from nuget.org via the package Hedgehog.XUnit.

[moodmosaic]

🚀

[moodmosaic]

https://twitter.com/nikosbaxevanis/status/1346496761196662784