Hello ERC20 Permit

npm i

# Test signature verification
npx hardhat test test/verify-signature.js

# Test ERC20 Permit
npx hardhat test test/erc20-permit.js

Links

https://docs.ethers.io/v5/api/signer/#Signer-signMessage

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/extensions/draft-IERC20Permit.sol

https://github.com/Uniswap/v3-periphery/blob/main/test/shared/permit.ts