Add Strings.toString for signed integers

[galadd]

• Tests
• Documentation
• Changelog entry

[Amxx]

Hello, @gbolahananon

Considering that we already have SignedMath:abs(int256) and Strings.toString(uint256), I think the implementation could be greatly simplified.

function toString(int256 value) internal pure returns (string memory) {
    return string.packed(value < 0 ? "-" : "", toString(abs(value));
}

[galadd]

That makes sense. I just implemented that. You can check the latest update

[Amxx]

Any reason to do string(abi.encodePacked(...)) and not string.concat(...)? I think the second one is clearer and cleaner

[galadd]

I used abi.encodePacked because it works with previous version of solidity and if a beginner wants to use the library, they aren’t faced with much difficulty. But on second thought, it's better a beginner gets used to the new implementation.

I have made a new commit

[Amxx]

That would require bumping the pragma from pragma solidity ^0.8.0; to pragma solidity ^0.8.12; ...

It not just a matter of beginner devs, but also of good support with big projects that are fixing a solidity version that is before 0.8.12.

Considering we can do without the pragma bump, you might be right that we should probable use string(abi.encodePacked(...)).

[galadd]

Alright then, I think it's all good to go 👍🏽

[galadd]

This PR has not been merged. Is there any change I need to effect?

[Amxx]

We are still missing a Changelog entry for this PR.

[Amxx]

Note: I'd love #3666 to be merge first, so that the tests can use the new syntax (instead of having to update #3666 yet again)

[frangio]

LGTM

[ernestognw]

For the record, let's group tests by type so they don't mix with each other

describe('toString', function () {
  ...
  describe('int256', function () { ... });
  describe('uint256', function () { ... });
  ...
})

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