petejkim

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

interface IERC20 {
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address to, uint256 value) external returns (bool);

petejkim

import BN from "bn.js";
import * as types from "./types";

test("decimalStringFromBN", () => {
  expect(types.decimalStringFromBN(new BN(0))).toEqual("0");
  expect(types.decimalStringFromBN(new BN(0), 1)).toEqual("0");
  expect(types.decimalStringFromBN(new BN(1000000))).toEqual("1000000");
  expect(types.decimalStringFromBN(new BN(1000000), 1)).toEqual("100000");
  expect(types.decimalStringFromBN(new BN(1000001), 1)).toEqual("100000.1");
  expect(types.decimalStringFromBN(new BN(1000100), 1)).toEqual("100010");

petejkim

$ ganache-cli --fork <NODE_RPC_URL> --chainId 1 --secure --unlock <ADMIN_ADDRESS>

petejkim

// Storage slot 9 contains "balances" (mapping(address => uint256))
// Derive slot position for the key k
const k = holderAddr.slice(2).toLowerCase().padStart(64, "0");
const p = "9".padStart(64, "0");
const valueSlotPos = web3.utils.keccak256("0x" + k + p);
const data = await web3.eth.getStorageAt(contract.address, valueSlotPos);

expect(new BN(data.slice(2), 16).eq(expectedBalance)).to.be.true;

petejkim

// Storage slot 4 contains "name" (string)
const data = await web3.eth.getStorageAt(contract.address, 4);
const len2 = parseInt(data.slice(-2), 16); // Last 1 byte = length * 2
// Read the text (skip "0x")
const text = Buffer.from(data.slice(2, 2 + len2), "hex").toString("utf8");

expect(text).to.equal(name);

petejkim

// Storage slot 1 contains "pauser" (bool) and "paused" (address)
const data = await web3.eth.getStorageAt(contract.address, 1);
const pauserData = data.slice(-40);       // Take the last 20 bytes
const pausedData = data.slice(-42, -40);  // Take 1 byte before that

expect(pauserData).to.equal(pauserAddress.slice(2).toLowerCase());
expect(!!parseInt(pausedData, 16)).to.equal(paused); // Convert to boolean

petejkim

// Storage slot 0 contains "owner" (address)
const data = await web3.eth.getStorageAt(contract.address, 0);
// Take the last 20 bytes, left-pad with zeros if needed
const ownerData = data.slice(-40).padStart(40, "0"); 

expect(ownerData).to.equal(
  ownerAddress.slice(2).toLowerCase() // Remove "0x"
);

petejkim

contract Foo {
    bytes32 private constant NUM_SLOT = keccak256("Foo.num");
    
    function num() public view returns (uint256 val) {
        bytes32 slot = NUM_SLOT;
        assembly {
            val := sload(slot)
        }
    }
    

petejkim

// SPDX-License-Identifier: MIT
// Copyright (c) 2020 petejkim

pragma solidity 0.6.12;

import { Ownable } from "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.2.0/contracts/access/Ownable.sol";
import { IERC20 } from "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.2.0/contracts/token/ERC20/IERC20.sol";
import { SafeERC20 } from "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.2.0/contracts/token/ERC20/SafeERC20.sol";

contract USDCFaucet is Ownable {

petejkim

test("decimalStringFromBN", () => {
  expect(types.decimalStringFromBN(new BN(0))).toEqual("0");
  expect(types.decimalStringFromBN(new BN(0), 1)).toEqual("0");
  expect(types.decimalStringFromBN(new BN(1000000))).toEqual("1000000");
  expect(types.decimalStringFromBN(new BN(1000000), 1)).toEqual("100000");
  expect(types.decimalStringFromBN(new BN(1000001), 1)).toEqual("100000.1");
  expect(types.decimalStringFromBN(new BN(1000100), 1)).toEqual("100010");
  expect(types.decimalStringFromBN(new BN(1000000), 2)).toEqual("10000");
  expect(types.decimalStringFromBN(new BN(1000001), 2)).toEqual("10000.01");
  expect(types.decimalStringFromBN(new BN(1000100), 2)).toEqual("10001");