Contract state is no longer required to implement StateClone for unit testing

[target-san]

Purpose

Remove StateClone trait, which was needed only to clone toplevel contract state during unit testing

Changes

• TestHost implementation no longer imposes StateClone constraint onto state type
• State is cloned by deserializing it from storage
• StateClone is removed (see comment)

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG.

CLA acceptance

By submitting the contribution I accept the terms and conditions of the
Contributor License Agreement v1.0

• link: https://developers.concordium.com/CLAs/Contributor-License-Agreement-v1.0.pdf

• I accept the above linked CLA.

[target-san]

One thing which I didn't touch is whether TestHost::with_rollback should be modified to perform actual operation on cloned state and leave original state as-is, just in case

[abizjak]

Hi. thanks for the effort.

We were planning to deprecate the entire test infrastructure as it is now in favor of the testing library and with that we would remove in particular the StateClone, but also the odd and hard to explain "state_parameter = S" annotation on the macros, and a few generics on entrypoints.

I would prefer to do that in one big release, rather than deprecating/removing things one at a time.

Is this blocking you?

If it is, I don't think deprecating is the right approach. People should not be writing these by hand anyhow, so we should just remove the StateClone trait entirely.

[target-san]

Well, this test infra is kind of useful in some scenarios 'cause it allows debugging contract directly.

Nope, it's not blocking me or anything. Just had some spare time and inspiration to drop it. Thought that soft deprecation is better, as it won't break other users' code. Shall I remove StateClone completely?

[abizjak]

Well, this test infra is kind of useful in some scenarios 'cause it allows debugging contract directly.

Sure, but the issue is that it adds a lot of complexity, both in terms of the way the contracts look (with extra generics), and with the amount of code we need to maintain (for example the entire implementation of test infrastructure, including its own state implementation). So our conclusion is that iti s not worth it.

Nope, it's not blocking me or anything. Just had some spare time and inspiration to drop it. Thought that soft deprecation is better, as it won't break other users' code. Shall I remove StateClone completely?

Yes, that'd be my preference.

[target-san]

I dropped StateClone completely, both in this repo and in concordium-contracts-common: please check PR 104
Unfortunately this one's incomplete, as I'll have to fix smart contract templates checking on CI

[target-san]

Ok, so StateClone is now completely removed, and all checks are fixed.
Plz note that PR 104 should be merged first in order to set proper submodule reference

[abizjak]

Looks good.

Sorry for the tardiness here as well. This will be released on Monday.

I have merged it into #330