🦋 FlyDex

FlyDex is a decentralized token exchange built with Solidity and Foundry. It allows users to swap tokens, add/remove liquidity, and collect protocol fees, integrating directly with Uniswap V2 on Arbitrum. It includes production-ready patterns like reentrancy protection, fee tracking, slippage, clean architecture, and comprehensive test coverage.

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✨ Features

• 🔁 Swap ERC20 tokens
• 🔁 Swap ETH for ERC20 tokens
• ➕ Add liquidity to ERC20-ERC20 pools
• ➕ Add liquidity to ETH-ERC20 pools
• ➖ Remove liquidity from ERC20-ERC20 pools
• ➖ Remove liquidity from ETH-ERC20 pools
• 💰 Customizable fee mechanism (set by owner)
• 🔓 Only owner can withdraw accumulated fees
• 🛡️ Reentrancy protection on sensitive functions
• 📢 Event emission for all features
• 🧪 Complete unit tests and fuzzing with Foundry
• 🔄 Forked mainnet testing (Arbitrum One)

🔐 Security Measures

• Reentrancy protection using OpenZeppelin's ReentrancyGuard on sensitive functions like withdrawFees.
• Use of SafeERC20 for all token transfers to handle non-standard ERC20 tokens.
• Owner-only functions protected with Ownable.
• Event logging for transparency and easier off-chain tracking.
• Fes tracked per-token to avoid mixing funds.
• Fee percentage capped at 5% to prevent excessive charges.
• ETH tracked separately via address(0) in fee mappings.

🧪 Tests

All core functionalities are tested using Foundry:

• ✅ swapTokens()
• ✅ swapETHForTokens()
• ✅ addLiquidityTokens()
• ✅ addLiquidityETH()
• ✅ removeLiquidity()
• ✅ removeLiquidityETH()
• ✅ changeFee()
• ✅ withdrawFees()
• ✅ Fuzzing tests for swap paths and amounts
• ✅ Invariant test for fee consistency
• ✅ Revert tests for negative scenarios

Run tests with:

forge test --fork-url https://arb1.arbitrum.io/rpc --match-test test_swapTokens

🧠 Technologies Used

• Solidity (^0.8.24)
• Foundry – Smart contract development & testing framework
• Uniswap V2 – Token swap & liquidity router
• OpenZeppelin Contracts – Ownable, ReentrancyGuard, SafeERC20
• Arbitrum One – Mainnet fork for realistic tests

📜 License

This project is licensed under the MIT License.