🛒 NFT Marketplace – Minimal On-Chain Marketplace in Solidity

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📌 Project Overview

NFT Marketplace is a professionally crafted, gas-efficient smart contract project enabling the secure listing, purchasing, and cancellation of ERC721 (NFT) tokens on-chain. It showcases robust Solidity engineering practices including:

• CEI (Checks-Effects-Interactions) pattern
• Non-reentrancy protection via ReentrancyGuard
• Access control using OpenZeppelin's Ownable
• Extensive testing and revert condition coverage using Foundry

This project is designed to be modular, easily extendable, and a solid base for real-world decentralized NFT trading platforms.

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🧱 Core Features

• NFT Listing: Owners can list their NFTs with a custom price.
• NFT Purchase: Buyers can purchase NFTs using exact ETH payments.
• Listing Cancellation: Sellers can cancel listings anytime before a sale.
• Ownership Check: Only NFT owners can list or cancel.
• ETH Transfer Handling: Robust payment flow with fallback protection.

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📁 File structure

├── src/
│   ├── NFTMarketplace.sol     # Marketplace logic
│   └── RejectETH.sol          # Utility contract to simulate ETH transfer reverts
├── test/
│   └── NFTMarketplace.t.sol   # Full test suite using Foundry

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🧱 Contract Overview

Struct: Listing

struct Listing {
    address seller;
    address nftAddress;
    uint256 tokenId;
    uint256 price;
}

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🚀 Features

• ✅ List NFTs with custom price
• 💸 Buy listed NFTs by paying exact ETH amount
• ❌ Cancel listing if still owner
• 🔐 ReentrancyGuard and CEI pattern for safe value transfer
• 🧪 Comprehensive testing including transfer reverts

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🔐 Access Control

• Only the NFT owner can list
• Only the original lister can cancel
• Anyone can buy if price matches listing

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⚠️ Error Handling

• Price cannot be zero
• You are not the owner of the NFT
• Listing not found
• Incorrect amount
• You did not list this token
• Transfer failed

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🧪 Testing

Tested with Foundry, including:

• Valid and invalid listings
• Successful and failing purchases
• Owner validation and reverts
• Transfer failure handling using RejectETH

Test Coverage: ✅ 100%

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📄 License

Licensed under the GNU Lesser General Public License v3.0 – see the LICENSE file.

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🙋‍♂️ Maintainer

This repository is maintained by an independent Solidity developer focused on clear, secure, and testable smart contract design.