openzeppelin-contracts/test/helpers/create.js

const { rlp } = require('ethereumjs-util');

function computeCreateAddress(deployer, nonce) {
  return web3.utils.toChecksumAddress(web3.utils.sha3(rlp.encode([deployer.address ?? deployer, nonce])).slice(-40));
}

function computeCreate2Address(saltHex, bytecode, deployer) {
  return web3.utils.toChecksumAddress(
    web3.utils
      .sha3(
        '0x' +
          ['ff', deployer.address ?? deployer, saltHex, web3.utils.soliditySha3(bytecode)]
            .map(x => x.replace(/0x/, ''))
            .join(''),
      )
      .slice(-40),
  );
}

module.exports = {
  computeCreateAddress,
  computeCreate2Address,
};