test.ts

import hre, { ethers } from "hardhat";
import { Contract } from "ethers";

describe("Forking", function () {
  it("Should fork mainnet4", async function () {
    const mainnetTestAccountAddress = "0x618d17fa59c67aEA20A88dc75d4E28E728a6fF28";
    const usdcAbi = require("@openzeppelin/contracts/build/contracts/IERC20.json").abi;
    const usdcAddress = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";

    // check the block number
    const blockNumber = await ethers.provider.getBlockNumber();
    console.log("blocknumber", blockNumber); // blocknumber 14715419

    // impersonate test account
    await hre.network.provider.request({
      method: "hardhat_impersonateAccount",
      params: [mainnetTestAccountAddress],
    });

    // check eth balance
    const ethBalance = await ethers.provider.getBalance(mainnetTestAccountAddress);
    console.log("eth balance:", ethers.utils.formatEther(ethBalance)); // eth balance: 15.315010386254091492

    // check usdc balance
    const testAccount = await ethers.getSigner(mainnetTestAccountAddress);
    const USDCContract: Contract = new ethers.Contract(usdcAddress, usdcAbi, testAccount);
    // ERROR
    await USDCContract.connect(testAccount).balanceOf(mainnetTestAccountAddress);
  });
});