🖼️ NFT Marketplace

📝 Overview

NFT Marketplace is a minimalist yet functional smart contract that enables users to list, buy, and cancel ERC-721 NFTs directly on-chain at a fixed price. The contract provides a simple and secure interface for peer-to-peer NFT trading using native ETH. Built with Solidity and tested using Foundry, the marketplace prioritizes security, correctness, and gas-efficiency.

✨ Features

• 🏷️ List NFTs: Owners can list their NFTs for a specific price.
• 💰 Buy NFTs: Buyers can purchase listed NFTs by paying the exact price.
• ❌ Cancel Listings: Sellers can cancel their active listings.
• 🔐 Security Measures:
  • Reentrancy protection using OpenZeppelin’s ReentrancyGuard
  • Checks for ownership and price correctness
• 📢 Events: Emits NFTListed, NFTSold, and NFTCanceled for front-end and analytics integration.

🧩🛡️ Contract Logic & Security Practices

• Storage Layout: Nested mapping(address => mapping(uint256 => Listing)) for quick NFT listing lookups.
• Structs:
  • Listing: Stores seller, NFT address, token ID, and price.
• Events:
  • NFTListed, NFTSold, NFTCanceled to track contract activity.
• Modifiers & Checks:
  • Ownership verification with IERC721.ownerOf
  • ReentrancyGuard used to avoid reentrancy attacks
• Design Patterns:
  • CEI (Checks-Effects-Interactions)
  • Pull payment patern using .call{value: msg.value}("")
• Gas Optimization:
  • Minimal storage and logic to reduce execution costs.

🧪 Testing

The contract includes a complete suite of unit tests using Foundry’s forge-std/Test.sol. Tests validate core functionalities, expected behavior, and edge cases:

Test Function	Purpose
testMintNFT()	Verifies NFT minting in test setup
testShouldRevertIfPriceIsZero()	Prevents listing with price = 0
testShouldRevertIfNotOwner()	Blocks non-owners from listing
testListNFTCorrectly()	Confirms successful listing
testListShouldRevertIfNotOwner()	Prevents cancellation by non-seller
testCancelListShouldWorkCorrectly()	Allows correct cancellation of listing
testCanNotBuyUnlistedNFT()	Prevents unlisted NFT purchase
testCanNotBuyWithIncorrectPay()	Validates exact payment enforcement
testShouldBuyNFTCorrectly()	Confirms full purchase flow (ownership + ETH transfer)

✅ Coverage Highlights

forge coverage

📈 95%+ test coverage, including listing, cancel listing, and buying.

File	% Lines	% Statements	% Branches	% Funcs
src/NFTMarketplace.sol	100.00% (21/21)	100.00% (20/20)	91.67% (11/12)	100.00% (3/3)

🔍 Notes:

• ETH transfer require(success, ...) fallback path intentionally not tested (very low risk)

The uncovered lines do not affect contract behavior or introduce security risk.

🛠 Technologies Used

• Solidity: Solidity ^0.8.24
• Testing: Foundry (Forge)
• NFT Standard: ERC721
• Security: ReentrancyGuard (OpenZeppelin)

🔧 How to Use

Prerequisites

• Install Foundry
• Install OpenZeppelin

🛠 Setup

git clone https://github.com/your-username/NFTMarketplace.git
cd NFTMarketplace
forge install

Testing

forge test
forge --match-test testExample -vvvv

📜 License

This project is licensed under the MIT License.