EVM DeFi Lending Protocol

A complete Solidity-based DeFi lending protocol inspired by Aave V3, built on EVM-compatible blockchains. This protocol enables users to supply assets as collateral, borrow against their collateral, and earn interest on supplied assets.

📋 Table of Contents

• Features
• Architecture
• Project Structure
• Setup
• Testing
• Deployment
• Contact

✨ Features

Core Functionality

• Asset Supplying: Users can supply ERC20 tokens to earn interest
• Borrowing: Users can borrow assets against their supplied collateral
• Variable Interest Rates: Dynamic interest rates based on utilization
• Flash Loans: Uncollateralized loans within a single transaction
• Liquidation: Automatic liquidation of undercollateralized positions
• Interest Accrual: Real-time interest accrual for both suppliers and borrowers

Technical Features

• Multiple Reserves: Support for multiple ERC20 assets (DAI, USDC, WETH, etc.)
• Price Oracles: Integration with price oracles for collateral valuation
• Access Control: Role-based access control for admin functions
• Pausability: Emergency pause functionality
• Reentrancy Protection: Guards against reentrancy attacks
• Gas Optimized: Efficient storage and computation patterns

🏗️ Architecture

┌─────────────────────────────────────────────────────────────┐
│                         Users                               │
└────────────────────┬────────────────────────────────────────┘
                     │
                     ▼
┌─────────────────────────────────────────────────────────────┐
│                      Pool Contract                          │
│  (Main entry point for all user interactions)               │
│  - supply()                                                  │
│  - withdraw()                                               │
│  - borrow()                                                 │
│  - repay()                                                  │
│  - flashLoan()                                              │
│  - liquidationCall()                                         │
└──────┬──────────────┬──────────────┬────────────────────────┘
       │              │              │
       ▼              ▼              ▼
┌─────────────┐ ┌─────────────┐ ┌─────────────┐
│   AToken    │ │ VariableDebt│ │ StableDebt  │
│  (Supply)   │ │    Token    │ │    Token    │
└─────────────┘ └─────────────┘ └─────────────┘
       │              │              │
       └──────────────┴──────────────┘
                     │
       ┌─────────────┴─────────────┐
       │                           │
       ▼                           ▼
┌──────────────┐          ┌──────────────────┐
│ Price Oracle │          │ Interest Rate    │
│              │          │ Strategy         │
└──────────────┘          └──────────────────┘

Contract Components

1. Pool: Main contract handling all user interactions
2. AToken: Interest-bearing tokens representing supplied assets
3. VariableDebtToken: Tokens representing variable-rate debt
4. StableDebtToken: Tokens representing stable-rate debt
5. DefaultReserveInterestRateStrategy: Calculates interest rates based on utilization
6. PriceOracle: Provides asset prices for collateral valuation

📁 Project Structure

evm-defi-lending-protocol/
├── contracts/
│   ├── interfaces/
│   │   ├── IPool.sol
│   │   ├── IAToken.sol
│   │   ├── IDebtToken.sol
│   │   ├── IPriceOracle.sol
│   │   ├── IInterestRateStrategy.sol
│   │   └── IFlashLoanReceiver.sol
│   ├── libraries/
│   │   ├── ReserveConfiguration.sol
│   │   ├── WadRayMath.sol
│   │   └── MathUtils.sol
│   ├── protocol/
│   │   ├── pool/
│   │   │   ├── Pool.sol
│   │   │   └── DefaultReserveInterestRateStrategy.sol
│   │   ├── tokenization/
│   │   │   ├── AToken.sol
│   │   │   ├── VariableDebtToken.sol
│   │   │   └── StableDebtToken.sol
│   │   ├── oracle/
│   │   │   └── PriceOracle.sol
│   │   └── libraries/
│   │       └── types/
│   │           └── DataTypes.sol
│   └── mocks/
│       ├── MockERC20.sol
│       ├── MockDAI.sol
│       ├── MockUSDC.sol
│       ├── MockWETH.sol
│       ├── MockChainlinkAggregator.sol
│       └── MockFlashLoanReceiver.sol
├── scripts/
│   └── deploy.js
├── test/
│   ├── Pool.test.js
│   ├── AToken.test.js
│   └── InterestRateStrategy.test.js
├── hardhat.config.js
├── helper-hardhat-config.js
├── package.json
└── README.md

🚀 Setup

Prerequisites

• Node.js (v16 or higher)
• npm or yarn
• Git

Installation

1. Clone the repository:

cd lending-protocol

2. Install dependencies:

npm install
# or
yarn install

3. Create a .env file (optional, for testnet deployment):

cp .env.example .env

Edit .env and add your private key and RPC URLs:

PRIVATE_KEY=your_private_key_here
SEPOLIA_RPC_URL=https://sepolia.infura.io/v3/your_key
ETHERSCAN_API_KEY=your_etherscan_api_key

4. Compile the contracts:

npx hardhat compile

🧪 Testing

Run the test suite:

npx hardhat test

Run specific test files:

npx hardhat test test/Pool.test.js
npx hardhat test test/AToken.test.js
npx hardhat test test/InterestRateStrategy.test.js

Run tests with gas reporting:

REPORT_GAS=true npx hardhat test

Test Coverage

The test suite covers:

• ✅ Asset supplying and withdrawal
• ✅ Borrowing and repayment
• ✅ Interest rate calculations
• ✅ Flash loans
• ✅ Liquidation mechanics
• ✅ Edge cases (zero amounts, insufficient balance, etc.)

🚢 Deployment

Local Network

1. Start a local Hardhat node:

npx hardhat node

2. In another terminal, deploy to localhost:

npx hardhat run scripts/deploy.js --network localhost

Testnet Deployment (Sepolia)

1. Ensure your .env file is configured with:

   • PRIVATE_KEY: Your wallet private key
   • SEPOLIA_RPC_URL: Sepolia RPC endpoint
   • ETHERSCAN_API_KEY: Etherscan API key (for verification)

2. Deploy to Sepolia:

npx hardhat run scripts/deploy.js --network sepolia

3. Verify contracts (optional):

npx hardhat verify --network sepolia <CONTRACT_ADDRESS> <CONSTRUCTOR_ARGS>

📧 Contact

• Telegram: https://t.me/rouncey
• Twitter: https://x.com/rouncey_