fix/etherscan verification

[rkrasiuk]

Motivation

Solution

PR Checklist

• Added Tests
• Added Documentation
• Updated the changelog

[mattsse]

what could be nice to have is some roundtrip test:

1. get contract source code for a specific address
2. get metadata (hopefully compiler version and constructor arguments are included)
3. call verify

[gakonst]

@rkrasiuk FYI #809 got rolled in #802 so if you'd want to unblock yourself from it you could use that as the base for this PR. Otherwise, will ping again when 802 is merged and we can then move forward with it (+ add a roundtrip test)?

[rkrasiuk]

@gakonst what do you think about the following - I add a roundtrip test and we merge as it is. then, in foundry, we require to provide the compiler version and num of optimizations for now. then, after #802 is merged, we just improve on top of this PR. that would solve a lot of current complaints about verification that users have

[gakonst]

agreed - sgtm

[rkrasiuk]

@gakonst perfect, will take care of this tmrw morning

[rkrasiuk]

@mattsse so, the metadata is all there in the response. the problem with the roundtrip test is that etherscan would error out on trying to verify the contract that was already verified. i guess we can redeploy the contract each time on goerli for verification, but we'd have to set up some dummy wallet with goerli eth

[mattsse]

oh I see, I don't think that's worth it.
looking good!

[gakonst]

Looks good! Let's maybe look into how we can expand flattening to support multiple contracts In the same file?