Lint

hardhat.config.js

 const fs = require('fs');
 const path = require('path');
 
-require("@nomiclabs/hardhat-truffle5");
-require("@nomiclabs/hardhat-solhint");
-require("solidity-coverage");
+require('@nomiclabs/hardhat-truffle5');
+require('@nomiclabs/hardhat-solhint');
+require('solidity-coverage');
 
 for (const f of fs.readdirSync(path.join(__dirname, 'hardhat'))) {
   require(path.join(__dirname, 'hardhat', f));
@@ -13,7 +13,7 @@ for (const f of fs.readdirSync(path.join(__dirname, 'hardhat'))) {
  * @type import('hardhat/config').HardhatUserConfig
  */
 module.exports = {
-  solidity: "0.8.0",
+  solidity: '0.8.0',
   settings: {
     optimizer: {
       enabled: false,

test/math/SafeMath.test.js

@@ -26,7 +26,7 @@ contract('SafeMath', function (accounts) {
   }
 
   async function testFailsCommutative (fn, lhs, rhs, reason, ...extra) {
-    if (reason == undefined) {
+    if (reason === undefined) {
       await expectRevert.unspecified(fn(lhs, rhs, ...extra));
       await expectRevert.unspecified(fn(rhs, lhs, ...extra));
     } else {

test/proxy/UpgradeableProxy.behaviour.js

@@ -5,10 +5,6 @@ const { expect } = require('chai');
 
 const DummyImplementation = artifacts.require('DummyImplementation');
 
-function toChecksumAddress (address) {
-  return ethereumjsUtil.toChecksumAddress('0x' + address.replace(/^0x/, '').padStart(40, '0').substr(-40));
-}
-
 const IMPLEMENTATION_LABEL = 'eip1967.proxy.implementation';
 
 function toChecksumAddress (address) {