🛒 FLYMarketplace

📝 Overview

FLYMarketplace s a professional smart contract for listing, buying, and canceling ERC-721 NFTs with monetization mechanisms and production-ready controls, such as pausable states, owner-only access, and proper ETH flow mechanisms. It introduces dynamic fees, withdrawal systems, pausability, and extensive testing using Foundry.

✨ Features

• 🏧 List NFTs: Sellers can list NFTs for a specific price and pay a configurable listing fee.
• 💰 Buy NFTs: Buyers can purchase NFTs by paying the sale price plus a configurable fee.
• ❌ Cancel Listings: Sellers can cancel their own active listings.
• 🔐 Security Measures:
  • Reentrancy protection using OpenZeppelin’s ReentrancyGuard
  • Pausable mechanism for emergency stops
  • Ownership-based access control using Ownable
  • 💸 Fee Management:
  • Dynamic listFee and buyFee managed by the owner
  • Accumulated fees can be withdrawn via withdrawFees()
• 📢 Events: Emits NFTListed, NFTSold, NFTCanceled, NFTFeeCollected and WithdrawnFees.

🧩🛡️ Contract Logic & Security Practices

• Storage Layout: Nested mapping(address => mapping(uint256 => Listing)) for direct NFT lookups.
• Structs:
  • Listing: Stores seller, NFT address, token ID, and price.
• Events:
  • NFTListed, NFTSold, NFTCanceled, NFTFeeCollected and WithdrawnFees 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}("")
• Security Extensions:
  • pause()and unpause() for emergency control.
  • onlyOwner protectioin on fee setters and withdraw function

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🧪 Testing

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

Test Function	Purpose
test_MintNFT()	Verifies NFT minting in test setup
test_ListNFTCorrectly()	Confirms correct listing with fee
test_ShouldBuyNFTCorrectly()	Full purchase flow with balance checks
test_CancelListShouldWorkCorrectly()	Cancels listing by correct seller
test_RevertsIfIncorrectFee()	Rejects incorrect listing fee
test_RevertsIfPriceIsZero()	Rejects zero price listing
test_RevertsIfNotOwner()	Prevents listing by non-owner
test_CancelListRevertsIfNotOwner()	Only lister can cancel listing
test_RevertsIfBuyUnlistedNFT()	Prevents purchase of unlisted NFT
test_RevertsIfBuyWithIncorrectPay()	Validates correct msg.value on buyNFT
test_withdrawFees()	Owner withdraws accumulated fees
test_RevertsIfNotFeesToWithdraw()	Prevents withdrawing zero fees
test_RevertsIfNotOwnerWithdraw()	Rejects fee withdrawal by non-owner
test_setListFeeCorrectly()	Sets new list fee by owner
test_setBuyFeeCorrectly()	Sets new buy fee by owner
test_revertsIfListFeeToHigh()	Rejects list fee above limit
test_revertsIfBuytFeeToHigh()	Rejects buy fee above limit
test_setListFeeRevertsIfNotOwner()	Only owner can change list fee
test_setBuyFeeRevertsIfNotOwner()	Only owner can change buy fee
test_PauseAndUnpauseShouldWorkForOwner()	Owner can pause and unpause the contract
test_ListNFTShouldFailWhenPaused()	Listing fails if contract is paused
test_PauseShouldRevertIfNotOwner()	Non-owner cannot pause
test_UnpauseShouldRevertIfNotOwner()	Non-owner cannot unpause

✅ Coverage Highlights

forge coverage

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

File	% Lines	% Statements	% Branches	% Funcs
src/FLYMarketplace.sol	98.00% (49/50)	97.83% (45/46)	90.91% (20/22)	100.00% (9/9)

🔍 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, Ownable, Pausable (OpenZeppelin)

🔧 How to Use

Prerequisites

• Install Foundry
• Install OpenZeppelin

🛠 Setup

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

Testing

forge test
forge --match-test testExample -vvvv

📜 License

This project is licensed under the MIT License.