🏆 Raffle Smart Contract

Overview

This is a decentralized Raffle (lottery) smart contract built on Solidity, leveraging Chainlink VRF v2.5 for randomness and Chainlink Automation for periodic execution.

Author: @0xVishh
Inspired by: Cyfrin's Foundry Course (Patrick Collins)
Purpose: Learning & Experimentation

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🔧 Features

• 🎟 Enter a raffle by sending ETH
• ⏱ Automated upkeep using Chainlink Automation
• 🎲 Random winner selection via Chainlink VRF v2.5
• 🔒 Uses enum to manage state (OPEN, CALCULATING)
• 🧪 Fully tested with Foundry

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🧠 Architecture

• enterRaffle() — Players enter the raffle
• checkUpkeep() — Chainlink Automation determines if it's time to pick a winner
• performUpkeep() — Triggers Chainlink VRF request
• fulfillRandomWords() — Chainlink VRF returns randomness to select winner

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🧱 Tech Stack

• Solidity: ^0.8.19
• Foundry: Forge, Anvil
• Chainlink:
  • VRF v2.5 (randomness)
  • Automation (timed execution)
• Test Framework: Forge standard tests (.t.sol)
• Scripting: Deploy, interaction, and helper config scripts

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📂 Project Structure

.
├── contracts
│   └── Raffle.sol
├── script
│   ├── DeployRaffle.s.sol
│   ├── interactions.s.sol
│   └── HelperConfig.s.sol
├── test
│   └── RaffleTest.t.sol
├── lib
│   └── (Chainlink libraries & foundry-devops)
└── foundry.toml

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🚀 How to Deploy

1. Configure your .env with your Chainlink subscription ID, VRF details, etc.
2. Deploy:

forge script script/DeployRaffle.s.sol --rpc-url <your_rpc_url> --private-key <your_key> --broadcast

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🧪 Run Tests

forge test

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🔍 Learnings & Insights

• How Chainlink VRF v2.5 differs from older versions.
• Using Foundry for unit testing, mocking, and scripting.
• Automation-compatible contracts and the importance of checkUpkeep vs performUpkeep.
• Managing state machines in smart contracts.

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📜 License

MIT – Free for learning and educational purposes.