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Hardhat Essentials (ref)

1. Creating a new Hardhat project

mkdir hardhat-tutorial
cd hardhat-tutorial

npm init

npm install --save-dev hardhat

npx hardhat init

2. Hardhat's architecture

Hardhat is designed around the concepts of tasks and plugins.

2.1 Tasks

To see the currently available tasks in your project, run:

# List available tasks
npx hardhat

# Compile the smart contracts
npx hardhat compile

# Run the tests
npx hardhat test

2.2 Plugins

Hardhat is unopinionated in terms of what tools you end up using, but it does come with some built-in defaults. All of which can be overridden. Most of the time the way to use a given tool is by consuming a plugin that integrates it into Hardhat.

# Install the recommended plugin
npm install --save-dev @nomicfoundation/hardhat-toolbox

Add this line to the top of your hardhat.config.js:

require("@nomicfoundation/hardhat-toolbox");

3. Writing tests

• Contracts live inside a folder called contracts.
• Tests live inside a folder called test.

const [owner] = await ethers.getSigners();

=> Here we're getting a list of the accounts in the node we're connected to, which in this case is Hardhat Network, and we're only keeping the first one.

NOTE: Test setups can be re-used with fixtures.

4. Debugging with Hardhat Network

When running your contracts and tests on Hardhat Network you can print logging messages and contract variables calling console.log() from your Solidity code. To use it you have to import hardhat/console.sol in your contract code.

pragma solidity ^0.8.0;

import "hardhat/console.sol";

contract Token {
    // ...
    // Using console.log() inside a Solidity contract
    console.log(
        "Transferring from %s to %s %s tokens",
        msg.sender,
        to,
        amount
    );
    // ...
}

5. Deploying to a live network

Deployments are done through HardHat Ignition.

npx hardhat ignition deploy ./ignition/modules/Token.js --network sepolia

Read

6. Verify on Etherscan

npx hardhat ignition deploy ignition/modules/Lock.ts --network sepolia --verify

More

7. Contract Deployed at:

0x69A5C0E26FA12FcDfaD9E88e78e03054fAb107a8

EtherScan

https://holesky.etherscan.io/address/0x69A5C0E26FA12FcDfaD9E88e78e03054fAb107a8#code

8. Using OpenZeppelin contracts

npm install @openzeppelin/contracts

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

contract Box is Ownable {}

9. To deploy to HardHat local network

On one terminal

npx hardhat node

On a separate terminal:

npx hardhat ignition deploy ignition/modules/Escrow.ts --parameters ignition/parameters.json

10. Using HardHat vars

npx hardhat vars set INFURA_API_KEY
npx hardhat vars get INFURA_API_KEY
npx hardhat vars list

Then in hardhat.config.ts:

const INFURA_API_KEY = vars.get("INFURA_API_KEY");