https://github.com/yllvar/u2u-smart-contract
In this tutorial, you'll learn to create your first smart contract with Hardhat – a full-featured development environment for contract compilation, deployment and verification.
https://github.com/yllvar/u2u-smart-contract
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In this tutorial, you'll learn to create your first smart contract with Hardhat – a full-featured development environment for contract compilation, deployment and verification.
- Host: GitHub
- URL: https://github.com/yllvar/u2u-smart-contract
- Owner: yllvar
- Created: 2024-06-15T14:44:04.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2024-06-15T14:56:41.000Z (almost 2 years ago)
- Last Synced: 2025-02-17T23:42:01.738Z (over 1 year ago)
- Language: TypeScript
- Size: 68.4 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# First Smart Contract with Hardhat - U2U Tutorial
Welcome to this tutorial where you'll learn how to create your first smart contract using Hardhat – a comprehensive development environment for contract compilation, deployment, and verification.
## Table of Contents
- [Prerequisites](#prerequisites)
- [Initialization](#initialization)
- [Creating Your First Smart Contract](#creating-your-first-smart-contract)
- [Writing Automated Tests](#writing-automated-tests)
- [Deploying Your Smart Contract](#deploying-your-smart-contract)
## Prerequisites
Before we begin, make sure you are familiar with the following:
- Writing code in JavaScript
- Operating a terminal
- Using Git
- Understanding the basics of how smart contracts work
## Initialization
First, let's set up our Node.js environment for U2U smart contract development.
1. Create a folder for your project:
```sh
mkdir first-contract
cd first-contract
```
2. Create an empty Node.js project:
```sh
npm init -y
```
3. Add Hardhat as a dependency to the project:
```sh
npm install --save-dev hardhat
```
4. Initialize your Hardhat project:
```sh
npx hardhat init
```
5. Select "Create a TypeScript project" when prompted:
```
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888 888 "Y888888 888 "Y88888 888 888 "Y888888 "Y888
👷 Welcome to Hardhat v2.17.4 👷
? What do you want to do? …
Create a JavaScript project
❯ Create a TypeScript project
Create an empty hardhat.config.js
Quit
```
6. Follow the prompts to complete the setup:
```
✔ What do you want to do? · Create a TypeScript project
✔ Hardhat project root: · /path/to/your/project
✔ Do you want to add a .gitignore? (Y/n) · y
✔ Do you want to install this sample project's dependencies with npm (@nomicfoundation/hardhat-toolbox)? (Y/n) · y
```
Your project should now contain the following folders and files:
- `contracts/`
- `scripts/`
- `test/`
- `hardhat.config.ts`
## Creating Your First Smart Contract
1. Open the `contracts` folder and locate the `Lock.sol` file. This is a sample contract initialized by Hardhat.
2. `Lock.sol` is a simple time-locked wallet contract. Below is a breakdown of its components:
```solidity
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.9;
// Uncomment this line to use console.log
// import "hardhat/console.sol";
contract Lock {
uint public unlockTime;
address payable public owner;
event Withdrawal(uint amount, uint when);
constructor(uint _unlockTime) payable {
require(block.timestamp < _unlockTime, "Unlock time should be in the future");
unlockTime = _unlockTime;
owner = payable(msg.sender);
}
function withdraw() public {
// Uncomment this line, and the import of "hardhat/console.sol", to print a log in your terminal
// console.log("Unlock time is %o and block timestamp is %o", unlockTime, block.timestamp);
require(block.timestamp >= unlockTime, "You can't withdraw yet");
require(msg.sender == owner, "You aren't the owner");
emit Withdrawal(address(this).balance, block.timestamp);
owner.transfer(address(this).balance);
}
}
```
## Writing Automated Tests
To test our contract, we'll use Hardhat Network, a local blockchain network similar to U2U network. It comes built-in with Hardhat.
1. Open the `test` folder and delete the contents of `Lock.ts`.
2. Structure your test file like this:
```typescript
import { expect } from "chai";
import { ethers } from "hardhat";
import { time } from "@nomicfoundation/hardhat-toolbox/network-helpers";
describe("Lock", function () {
it("Should set the right unlockTime", async function () {
const ONE_YEAR_IN_SECS = 365 * 24 * 60 * 60;
const ONE_GWEI = 1_000_000_000;
const lockedAmount = ONE_GWEI;
const unlockTime = (await time.latest()) + ONE_YEAR_IN_SECS;
const Lock = await ethers.getContractFactory("Lock");
const lock = await Lock.deploy(unlockTime, { value: lockedAmount });
expect(await lock.unlockTime()).to.equal(unlockTime);
});
it("Should set the right owner", async function () {
const ONE_YEAR_IN_SECS = 365 * 24 * 60 * 60;
const ONE_GWEI = 1_000_000_000;
const lockedAmount = ONE_GWEI;
const unlockTime = (await time.latest()) + ONE_YEAR_IN_SECS;
const [owner] = await ethers.getSigners();
const Lock = await ethers.getContractFactory("Lock");
const lock = await Lock.deploy(unlockTime, { value: lockedAmount });
expect(await lock.owner()).to.equal(owner.address);
});
});
```
3. Run your tests:
```sh
npx hardhat test
```
## Deploying Your Smart Contract
After testing your contract, you can deploy it to the U2U network.
1. Create a deployment script `deploy.ts` in the `scripts` folder:
```typescript
import { ethers } from "hardhat";
async function main() {
const currentTimestampInSeconds = Math.round(Date.now() / 1000);
const unlockTime = currentTimestampInSeconds + 60;
const lockedAmount = ethers.parseEther("0.001");
const lock = await ethers.deployContract("Lock", [unlockTime], {
value: lockedAmount,
});
await lock.waitForDeployment();
console.log(
`Lock with ${ethers.formatEther(lockedAmount)} U2U and unlock timestamp ${unlockTime} deployed to ${lock.target}`
);
}
main().catch((error) => {
console.error(error);
process.exitCode = 1;
});
```
2. Configure the network in `hardhat.config.ts`:
```typescript
import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";
const config: HardhatUserConfig = {
solidity: "0.8.19",
networks: {
nebulas: {
url: 'https://rpc-nebulas-testnet.uniultra.xyz/',
accounts: ["YOUR_PRIVATE_KEY"], // it should start with 0x...
}
},
etherscan: {
apiKey: {
nebulas: "abc", // arbitrary string
},
customChains: [
{
network: "nebulas",
chainId: 2484,
urls: {
apiURL: "https://testnet.u2uscan.xyz/api",
browserURL: "https://testnet.u2uscan.xyz"
}
},
]
}
};
export default config;
```
3. Run the deployment script:
```sh
npx hardhat run scripts/deploy.ts --network nebulas
```