PoC: Integration tests with generic fudge environment

[lemunozm]

Description

Proof of concept to convert the env fudge module of integration-test in a Runtime independent way. So after this, test cases will be based on <T: Config> where T is the current runtime.

[lemunozm]

Common configuration between all our runtimes

[lemunozm]

The environment wraps different fudge::companion structs to be used independently of the runtime

[lemunozm]

Each runtime should implement the Environment and the Config

[lemunozm]

@mustermeiszer maybe the ideas from this PoC can be used to build the Option A of your thoughts here

[mustermeiszer]

I think my main problem is that test_with_all_runtimes assumes that the setup and so on is the same for all runtimes. Which I think is mostly true, but one essential breaking point are the differing AdminOrigin that we are using. Although, injecting via root should still work.

And tests would be generic over T: Config then?

[lemunozm]

Yes, the test would be generic over T: Config. I think procedural macros could be pretty obscure, and they are difficult to update if you do not have the required knowledge (actually, only you have such a power!). For me, as a rule of thumb, if you can avoid macros (decl or proc), then avoid them.

I think my main problem is that test_with_all_runtimes assumes that the setup and so on is the same for all runtimes.

Regarding this. The setup is the same only for those types you explicitly instantiate in pallet_xxx::Config. I mean, if I put in the Config trait a bound with pallet_balances::Config<Balance = u128>, then I assume all runtimes use u128, but if I leave it without the restriction, so just pallet_balances::Config, then each runtime could have their own Balance types. So, the idea is only restricted when you know all of our runtimes use the same types, if not, the types are not specified.

For things like AdminOrigin, where maybe the call in the test changes because of that, you can manually dispatch it with an if/match using T::KIND, for such border cases.

[lemunozm]

But I think, the big point of this PR (and challenge), is that the fudge::companion structs and associated methods and macros, can be abstracted by an Environtment trait. Also if they're abstracted, I think we no longer need macros as env::run or similar, they could be implemented in actual rust code.

[lemunozm]

Closed in favor of: #1588