evm-hardhat

Hardhat development for EVM chains including Celo. Use when setting up Hardhat projects, writing Solidity contracts, compiling, testing, deploying, or verifying contracts with Hardhat.

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Repository: celo-org/agent-skills
Last source activity: January 27, 2026 at 09:06
Detected SKILL.md language: English
Stars: 8
Forks: 4

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npx skills add https://github.com/celo-org/agent-skills --skill evm-hardhat

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SKILL.md

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import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";
import * as dotenv from "dotenv";

dotenv.config();

const PRIVATE_KEY = process.env.PRIVATE_KEY || "";
const CELOSCAN_API_KEY = process.env.CELOSCAN_API_KEY || "";

const config: HardhatUserConfig = {
  solidity: {
    version: "0.8.28",
    settings: {
      optimizer: {
        enabled: true,
        runs: 200,
      },
    },
  },
  networks: {
    // Celo Mainnet
    celo: {
      url: "https://forno.celo.org",
      chainId: 42220,
      accounts: PRIVATE_KEY ? [PRIVATE_KEY] : [],
    },
    // Celo Sepolia Testnet
    celoSepolia: {
      url: "https://forno.celo-sepolia.celo-testnet.org",
      chainId: 11142220,
      accounts: PRIVATE_KEY ? [PRIVATE_KEY] : [],
    },
    // Local development
    hardhat: {
      chainId: 31337,
    },
  },
  etherscan: {
    apiKey: {
      celo: CELOSCAN_API_KEY,
      celoSepolia: CELOSCAN_API_KEY,
    },
    customChains: [
      {
        network: "celo",
        chainId: 42220,
        urls: {
          apiURL: "https://api.celoscan.io/api",
          browserURL: "https://celoscan.io",
        },
      },
      {
        network: "celoSepolia",
        chainId: 11142220,
        urls: {
          apiURL: "https://api.etherscan.io/v2/api",
          browserURL: "https://sepolia.celoscan.io",
        },
      },
    ],
  },
};

export default config;

PRIVATE_KEY=your_private_key_here
CELOSCAN_API_KEY=your_celoscan_api_key_here

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.28;

contract MyContract {
    string public name;
    address public owner;

    event NameChanged(string oldName, string newName);

    modifier onlyOwner() {
        require(msg.sender == owner, "Not owner");
        _;
    }

    constructor(string memory _name) {
        name = _name;
        owner = msg.sender;
    }

    function setName(string memory _newName) external onlyOwner {
        string memory oldName = name;
        name = _newName;
        emit NameChanged(oldName, _newName);
    }
}

npm install @openzeppelin/contracts

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.28;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract MyToken is ERC20, Ownable {
    constructor() ERC20("MyToken", "MTK") Ownable(msg.sender) {
        _mint(msg.sender, 1000000 * 10 ** decimals());
    }

    function mint(address to, uint256 amount) external onlyOwner {
        _mint(to, amount);
    }
}

# Compile all contracts
npx hardhat compile

# Clean and recompile
npx hardhat clean && npx hardhat compile

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

describe("MyContract", function () {
  let contract: MyContract;
  let owner: any;
  let addr1: any;

  beforeEach(async function () {
    [owner, addr1] = await ethers.getSigners();
    const MyContract = await ethers.getContractFactory("MyContract");
    contract = await MyContract.deploy("Initial Name");
    await contract.waitForDeployment();
  });

  describe("Deployment", function () {
    it("Should set the right name", async function () {
      expect(await contract.name()).to.equal("Initial Name");
    });

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

  describe("setName", function () {
    it("Should allow owner to change name", async function () {
      await contract.setName("New Name");
      expect(await contract.name()).to.equal("New Name");
    });

    it("Should emit NameChanged event", async function () {
      await expect(contract.setName("New Name"))
        .to.emit(contract, "NameChanged")
        .withArgs("Initial Name", "New Name");
    });

    it("Should revert if non-owner tries to change name", async function () {
      await expect(
        contract.connect(addr1).setName("Hacked")
      ).to.be.revertedWith("Not owner");
    });
  });
});

# Run all tests
npx hardhat test

# Run specific test file
npx hardhat test test/MyContract.test.ts

# Run with gas reporting
REPORT_GAS=true npx hardhat test

# Run with coverage
npx hardhat coverage

// scripts/deploy.ts
import { ethers } from "hardhat";

async function main() {
  const [deployer] = await ethers.getSigners();
  console.log("Deploying with account:", deployer.address);

  const balance = await ethers.provider.getBalance(deployer.address);
  console.log("Account balance:", ethers.formatEther(balance), "CELO");

  const MyContract = await ethers.getContractFactory("MyContract");
  const contract = await MyContract.deploy("My Contract Name");
  await contract.waitForDeployment();

  const address = await contract.getAddress();
  console.log("Contract deployed to:", address);

  // Wait for confirmations before verification
  console.log("Waiting for confirmations...");
  await contract.deploymentTransaction()?.wait(5);

  console.log("Deployment complete!");
}

main()
  .then(() => process.exit(0))
  .catch((error) => {
    console.error(error);
    process.exit(1);
  });

# Deploy to local Hardhat network
npx hardhat run scripts/deploy.ts

# Deploy to Celo Sepolia testnet
npx hardhat run scripts/deploy.ts --network celoSepolia

# Deploy to Celo Mainnet
npx hardhat run scripts/deploy.ts --network celo

# Verify on Celo Sepolia
npx hardhat verify --network celoSepolia <CONTRACT_ADDRESS> "Constructor Arg 1"

# Verify on Celo Mainnet
npx hardhat verify --network celo <CONTRACT_ADDRESS> "Constructor Arg 1"

// Add to deployment script after deployment
import { run } from "hardhat";

async function verify(address: string, constructorArguments: any[]) {
  console.log("Verifying contract...");
  try {
    await run("verify:verify", {
      address,
      constructorArguments,
    });
    console.log("Verified!");
  } catch (e: any) {
    if (e.message.includes("Already Verified")) {
      console.log("Already verified");
    } else {
      console.error(e);
    }
  }
}

npx hardhat flatten contracts/MyContract.sol > Flattened.sol

npx hardhat compile --force
npx hardhat size-contracts

name	evm-hardhat
description	Hardhat development for EVM chains including Celo. Use when setting up Hardhat projects, writing Solidity contracts, compiling, testing, deploying, or verifying contracts with Hardhat.
license	Apache-2.0
metadata	{"author":"celo-org","version":"1.0.0"}

name	evm-hardhat
description	Hardhat development for EVM chains including Celo. Use when setting up Hardhat projects, writing Solidity contracts, compiling, testing, deploying, or verifying contracts with Hardhat.
license	Apache-2.0
metadata	{"author":"celo-org","version":"1.0.0"}

evm-hardhat

Install options

Review the source files

Hardhat Development for EVM Chains

When to Use

Quick Start

Initialize Project

Install Additional Dependencies

Celo Network Information

Hardhat Development for EVM Chains

When to Use

Quick Start

Initialize Project

Install Additional Dependencies

Celo Network Information

Configuration

hardhat.config.ts for Celo

Environment Variables (.env)

Writing Contracts

Basic Contract Structure

Using OpenZeppelin

Compilation

Testing

Test File Structure

Running Tests

Deployment

Deployment Script

Deploy Commands

Verification

Verify After Deployment

Programmatic Verification

Common Tasks

Flatten Contract for Manual Verification

Check Contract Size

Block Explorers

Additional Resources

evm-hardhat

Source facts

Install options

Review the source files

More from this repository

Hardhat Development for EVM Chains

When to Use

Quick Start

Initialize Project

Install Additional Dependencies

Celo Network Information

More from this repository

Hardhat Development for EVM Chains

When to Use

Quick Start

Initialize Project

Install Additional Dependencies

Celo Network Information

Configuration

hardhat.config.ts for Celo

Environment Variables (.env)

Writing Contracts

Basic Contract Structure

Using OpenZeppelin

Compilation

Testing

Test File Structure

Running Tests

Deployment

Deployment Script

Deploy Commands

Verification

Verify After Deployment

Programmatic Verification

Common Tasks

Flatten Contract for Manual Verification

Check Contract Size

Block Explorers

Additional Resources