Hardhat Framework Skill Skill

Hardhat Framework Skill

Expert-level usage of Hardhat, the most popular Ethereum development environment.

Capabilities

Configuration: Set up hardhat.config.js for multi-network
Testing: Write tests with ethers.js/viem
Plugins: Use plugins (upgrades, gas-reporter, coverage)
Local Network: Run Hardhat Network for development
Deployment: Execute scripts and manage deployments
Forking: Fork mainnet for testing
TypeChain: Generate TypeScript typings

Installation

# Create project
mkdir my-project && cd my-project
npm init -y

# Install Hardhat
npm install --save-dev hardhat

# Initialize project
npx hardhat init

# Install common dependencies
npm install --save-dev @nomicfoundation/hardhat-toolbox

Configuration

hardhat.config.js

require("@nomicfoundation/hardhat-toolbox");
require("@openzeppelin/hardhat-upgrades");
require("hardhat-gas-reporter");
require("solidity-coverage");

/** @type import('hardhat/config').HardhatUserConfig */
module.exports = {
  solidity: {
    version: "0.8.20",
    settings: {
      optimizer: {
        enabled: true,
        runs: 200,
      },
      viaIR: false,
    },
  },

  networks: {
    hardhat: {
      forking: {
        url: process.env.MAINNET_RPC_URL,
        blockNumber: 18000000,
      },
    },
    sepolia: {
      url: process.env.SEPOLIA_RPC_URL,
      accounts: [process.env.PRIVATE_KEY],
    },
    mainnet: {
      url: process.env.MAINNET_RPC_URL,
      accounts: [process.env.PRIVATE_KEY],
    },
  },

  etherscan: {
    apiKey: process.env.ETHERSCAN_API_KEY,
  },

  gasReporter: {
    enabled: true,
    currency: "USD",
    coinmarketcap: process.env.COINMARKETCAP_API_KEY,
  },

  paths: {
    sources: "./contracts",
    tests: "./test",
    cache: "./cache",
    artifacts: "./artifacts",
  },
};

TypeScript Configuration

// hardhat.config.ts
import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";
import "@openzeppelin/hardhat-upgrades";

const config: HardhatUserConfig = {
  solidity: "0.8.20",
  networks: {
    sepolia: {
      url: process.env.SEPOLIA_RPC_URL || "",
      accounts: process.env.PRIVATE_KEY ? [process.env.PRIVATE_KEY] : [],
    },
  },
};

export default config;

Testing

Basic Test

// test/Token.test.js
const { expect } = require("chai");
const { ethers } = require("hardhat");

describe("Token", function () {
  let token;
  let owner;
  let addr1;

  beforeEach(async function () {
    [owner, addr1] = await ethers.getSigners();

    const Token = await ethers.getContractFactory("Token");
    token = await Token.deploy();
    await token.waitForDeployment();
  });

  describe("Deployment", function () {
    it("Should set the right owner", async function () {
      expect(await token.owner()).to.equal(owner.address);
    });

    it("Should assign total supply to owner", async function () {
      const ownerBalance = await token.balanceOf(owner.address);
      expect(await token.totalSupply()).to.equal(ownerBalance);
    });
  });

  describe("Transactions", function () {
    it("Should transfer tokens", async function () {
      await token.transfer(addr1.address, 50);
      expect(await token.balanceOf(addr1.address)).to.equal(50);
    });

    it("Should emit Transfer event", async function () {
      await expect(token.transfer(addr1.address, 50))
        .to.emit(token, "Transfer")
        .withArgs(owner.address, addr1.address, 50);
    });

    it("Should fail if sender lacks funds", async function () {
      await expect(
        token.connect(addr1).transfer(owner.address, 1)
      ).to.be.revertedWith("Insufficient balance");
    });
  });
});

TypeScript Test

// test/Token.test.ts
import { expect } from "chai";
import { ethers } from "hardhat";
import { Token } from "../typechain-types";

describe("Token", function () {
  let token: Token;

  beforeEach(async function () {
    const Token = await ethers.getContractFactory("Token");
    token = await Token.deploy();
  });

  it("Should deploy successfully", async function () {
    expect(await token.getAddress()).to.be.properAddress;
  });
});

Fork Testing

const { expect } = require("chai");
const { ethers, network } = require("hardhat");

describe("Fork Test", function () {
  const USDC_ADDRESS = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
  const WHALE = "0x47ac0Fb4F2D84898e4D9E7b4DaB3C24507a6D503";

  beforeEach(async function () {
    // Impersonate whale account
    await network.provider.request({
      method: "hardhat_impersonateAccount",
      params: [WHALE],
    });
  });

  it("Should transfer USDC from whale", async function () {
    const whale = await ethers.getSigner(WHALE);
    const usdc = await ethers.getContractAt("IERC20", USDC_ADDRESS);

    const [, recipient] = await ethers.getSigners();
    const amount = ethers.parseUnits("1000", 6);

    await usdc.connect(whale).transfer(recipient.address, amount);
    expect(await usdc.balanceOf(recipient.address)).to.equal(amount);
  });
});

Deployment Scripts

Basic Deployment

// scripts/deploy.js
const hre = require("hardhat");

async function main() {
  const Token = await hre.ethers.getContractFactory("Token");
  const token = await Token.deploy();
  await token.waitForDeployment();

  console.log("Token deployed to:", await token.getAddress());

  // Verify on Etherscan
  if (hre.network.name !== "hardhat") {
    await hre.run("verify:verify", {
      address: await token.getAddress(),
      constructorArguments: [],
    });
  }
}

main().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});

Upgradeable Deployment

// scripts/deploy-upgradeable.js
const { ethers, upgrades } = require("hardhat");

async function main() {
  const Token = await ethers.getContractFactory("TokenV1");

  // Deploy proxy
  const token = await upgrades.deployProxy(Token, [], {
    initializer: "initialize",
  });
  await token.waitForDeployment();

  console.log("Proxy deployed to:", await token.getAddress());
}

main();

Upgrade Script

// scripts/upgrade.js
const { ethers, upgrades } = require("hardhat");

async function main() {
  const PROXY_ADDRESS = "0x...";

  const TokenV2 = await ethers.getContractFactory("TokenV2");
  const token = await upgrades.upgradeProxy(PROXY_ADDRESS, TokenV2);

  console.log("Token upgraded");
}

main();

Hardhat Tasks

// hardhat.config.js
task("accounts", "Prints accounts", async (taskArgs, hre) => {
  const accounts = await hre.ethers.getSigners();
  for (const account of accounts) {
    console.log(account.address);
  }
});

task("balance", "Prints balance")
  .addParam("account", "The account address")
  .setAction(async (taskArgs, hre) => {
    const balance = await hre.ethers.provider.getBalance(taskArgs.account);
    console.log(hre.ethers.formatEther(balance), "ETH");
  });

Commands

# Compile
npx hardhat compile

# Test
npx hardhat test
npx hardhat test --grep "transfer"

# Coverage
npx hardhat coverage

# Run script
npx hardhat run scripts/deploy.js --network sepolia

# Console
npx hardhat console --network localhost

# Node
npx hardhat node

# Verify
npx hardhat verify --network mainnet <address>

Process Integration

| Process | Purpose | |---------|---------| | smart-contract-development-lifecycle.js | Full development | | dapp-frontend-development.js | dApp integration | | All token processes | Token deployment | | All DeFi processes | Protocol deployment |

Best Practices

Use TypeScript for type safety
Configure multiple networks
Use environment variables
Enable gas reporting
Generate coverage reports
Verify contracts on explorers

Agent Skills: Hardhat Framework Skill

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