Foundry Smart Contract Lottery

Overview

Raffle is a smart contract lottery that utilizes Chainlink VRF to randomly select winners and Chainlink Automation to initialize a winner pick and restart of the lottery

This project demonstrates the implementation of a decentralized lottery system using:

• Chainlink VRF v2.5 for provably fair random number generation
• Chainlink Automation for automated lottery execution
• Foundry for development, testing, and deployment
• Solidity 0.8.19 for smart contract development

Features

• 🎰 Decentralized Lottery: Fair and transparent lottery system
• 🔗 Chainlink Integration: Uses VRF for randomness and Automation for execution
• 🛡️ Security: Implements CEI (Checks, Effects, Interactions) pattern
• 🧪 Comprehensive Testing: Unit tests with Foundry
• 🚀 Easy Deployment: Automated deployment scripts for multiple networks

Prerequisites

• Foundry installed
• Node.js and npm (for additional tooling if needed)
• Access to Ethereum RPC endpoints (Sepolia for testnet deployment)

Installation

1. Clone the repository:

git clone <repository-url>
cd foundry-smart-contract-lottery

2. Install dependencies:

make install

This will install:

• cyfrin/[email protected]
• smartcontractkit/[email protected]
• foundry-rs/[email protected]
• transmissions11/solmate@v6

Usage

Build

make build

Test

make test

Format Code

make fmt

Clean Build Artifacts

make clean

Generate Test Coverage Snapshot

make snapshot

Deployment

Environment Setup

Create a .env file with the following variables:

SEPOLIA_RPC_URL=your_sepolia_rpc_url
ETHERSCAN_API_KEY=your_etherscan_api_key
PRIVATE_KEY=your_private_key

Deploy to Local Anvil Network

make deploy

Deploy to Sepolia Testnet

make deploy-sepolia

Project Structure

├── src/
│   └── Raffle.sol              # Main lottery contract
├── test/
│   ├── unit/
│   │   └── RaffleTest.t.sol    # Unit tests
│   ├── integration/            # Integration tests
│   └── mocks/
│       └── LinkToken.sol       # Mock Chainlink token
├── script/
│   ├── DeployRaffle.s.sol      # Deployment script
│   ├── Interactions.s.sol      # Interaction script
│   └── HelperConfig.s.sol      # Configuration helper
├── lib/                        # Dependencies
├── foundry.toml               # Foundry configuration
├── Makefile                   # Build automation
└── README.md                  # This file

Smart Contract Features

Raffle Contract (src/Raffle.sol)

• Entrance Fee: Configurable fee to enter the lottery
• Time Interval: Configurable time between lottery rounds
• VRF Integration: Uses Chainlink VRF for random winner selection
• Automation: Uses Chainlink Automation for automated execution
• State Management: Tracks lottery state (OPEN/CALCULATING)
• Winner Selection: Fair random selection using VRF
• Prize Distribution: Automatic prize transfer to winner

Key Functions

• enterRaffle(): Enter the lottery by paying the entrance fee
• checkUpkeep(): Check if lottery is ready for winner selection
• performUpkeep(): Trigger winner selection process
• fulfillRandomWords(): Handle VRF callback and select winner

Testing

The project includes comprehensive unit tests covering:

• Lottery entry functionality
• Winner selection process
• VRF integration
• Automation triggers
• Error handling
• State management

Run tests with:

make test

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests for new functionality
5. Ensure all tests pass
6. Submit a pull request

License

This project is licensed under the MIT License.

Acknowledgments

• Chainlink for VRF and Automation services
• Foundry for the development framework
• Cyfrin for development best practices