evm-hardhat

# Hardhat Development for EVM Chains This skill covers Hardhat setup and development for EVM-compatible chains with emphasis on Celo. ## When to Use - Setting up a new Hardhat project - Writing and compiling Solidity smart contracts - Testing contracts with Hardhat - Deploying contracts to Celo or other EVM chains - Verifying contracts on block explorers ## Quick Start ### Initialize Project ```bash mkdir my-project && cd my-project npm init -y npm install --save-dev hardhat npx hardhat init ``` Select "Create a TypeScript project" when prompted. ### Install Additional Dependencies ```bash npm install --save-dev @nomicfoundation/hardhat-toolbox dotenv ``` ## Celo Network Information | Network | Chain ID | RPC Endpoint | |---------|----------|--------------| | Celo Mainnet | 42220 | https://forno.celo.org | | Celo Sepolia | 11142220 | https://forno.celo-sepolia.celo-testnet.org | ## Configuration ### hardhat.config.ts for Celo ```typescript 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; ``` ### Environment Variables (.env) ```bash PRIVATE_KEY=your_private_key_here CELOSCAN_API_KEY=your_celoscan_api_key_here ``` ## Writing Contracts ### Basic Contract Structure ```solidity // 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); } } ``` ### Using OpenZeppelin ```bash npm install @openzeppelin/contracts ``` ```solidity // 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); } } ``` ## Compilation ```bash # Compile all contracts npx hardhat compile # Clean and recompile npx hardhat clean && npx hardhat compile ``` ## Testing ### Test File Structure ```typescript // 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"); }); }); }); ``` ### Running Tests ```bash # 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 ``` ## Deployment ### Deployment Script ```typescript // 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 Commands ```bash # 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 ``` ## Verification ### Verify After Deployment ```bash # 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" ``` ### Programmatic Verification ```typescript // 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); } } } ``` ## Common Tasks ### Flatten Contract for Manual Verification ```bash npx hardhat flatten contracts/MyContract.sol > Flattened.sol ``` ### Check Contract Size ```bash npx hardhat compile --force npx hardhat size-contracts ``` ## Block Explorers - **Celo Mainnet:** https://celoscan.io - **Celo Sepolia:** https://sepolia.celoscan.io ## Additional Resources - [hardhat-config.md](references/hardhat-config.md) - Detailed configuration options - [testing-patterns.md](references/testing-patterns.md) - Advanced testing patterns - [security-checklist.md](rules/security-checklist.md) - Security best practices