Smart Contract Development Guide

Introduction

This guide covers the essential aspects of smart contract development, from planning to deployment. We'll explore best practices, tools, and workflows for building secure and efficient smart contracts.

Development Lifecycle

1. Planning Phase

• Requirements analysis
• Architecture design
• Security considerations
• Testing strategy

2. Development Phase

• Writing code
• Unit testing
• Integration testing
• Documentation

3. Deployment Phase

• Contract verification
• Network selection
• Gas optimization
• Monitoring

Development Environment

1. Local Setup

# Install Node.js and npm
# Download from https://nodejs.org/

# Install development framework
npm install --save-dev hardhat
# or
npm install -g truffle

# Install dependencies
npm install --save-dev @openzeppelin/contracts
npm install --save-dev @nomiclabs/hardhat-ethers
npm install --save-dev chai

2. Project Structure

project/
├── contracts/
│   ├── interfaces/
│   ├── libraries/
│   └── core/
├── scripts/
│   ├── deploy/
│   └── verify/
├── test/
│   ├── unit/
│   └── integration/
├── hardhat.config.js
└── package.json

Writing Smart Contracts

1. Contract Structure

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

contract MyContract is Ownable, ReentrancyGuard {
    // State variables
    
    // Events
    
    // Modifiers
    
    // Constructor
    
    // External functions
    
    // Public functions
    
    // Internal functions
    
    // Private functions
}

2. Security Patterns

contract SecureContract {
    // Reentrancy protection
    mapping(address => uint256) private balances;
    bool private locked;
    
    modifier noReentrant() {
        require(!locked, "No reentrancy");
        locked = true;
        _;
        locked = false;
    }
    
    function withdraw() external noReentrant {
        uint256 amount = balances[msg.sender];
        require(amount > 0, "No balance");
        
        balances[msg.sender] = 0;
        (bool success,) = msg.sender.call{value: amount}("");
        require(success, "Transfer failed");
    }
}

Testing

1. Unit Tests

const { expect } = require("chai");

describe("MyContract", function() {
    let contract;
    let owner;
    let user;
    
    beforeEach(async function() {
        const Contract = await ethers.getContractFactory("MyContract");
        [owner, user] = await ethers.getSigners();
        contract = await Contract.deploy();
        await contract.deployed();
    });
    
    it("Should perform expected action", async function() {
        await contract.connect(user).someFunction();
        expect(await contract.someValue()).to.equal(expectedValue);
    });
});

2. Integration Tests

describe("Integration", function() {
    it("Should interact with other contracts", async function() {
        // Deploy contracts
        const TokenA = await ethers.getContractFactory("TokenA");
        const TokenB = await ethers.getContractFactory("TokenB");
        const Exchange = await ethers.getContractFactory("Exchange");
        
        const tokenA = await TokenA.deploy();
        const tokenB = await TokenB.deploy();
        const exchange = await Exchange.deploy(tokenA.address, tokenB.address);
        
        // Test interactions
        await tokenA.approve(exchange.address, amount);
        await exchange.swap(amount);
        
        expect(await tokenB.balanceOf(user.address)).to.equal(expectedAmount);
    });
});

Deployment

1. Deployment Script

async function main() {
    // Get contract factory
    const Contract = await ethers.getContractFactory("MyContract");
    
    // Deploy contract
    const contract = await Contract.deploy(constructorArgs);
    await contract.deployed();
    
    console.log("Contract deployed to:", contract.address);
    
    // Verify contract
    await hre.run("verify:verify", {
        address: contract.address,
        constructorArguments: [constructorArgs],
    });
}

main()
    .then(() => process.exit(0))
    .catch(error => {
        console.error(error);
        process.exit(1);
    });

2. Network Configuration

// hardhat.config.js
module.exports = {
    networks: {
        hardhat: {
            // Local network
        },
        testnet: {
            url: process.env.TESTNET_URL,
            accounts: [process.env.PRIVATE_KEY],
        },
        mainnet: {
            url: process.env.MAINNET_URL,
            accounts: [process.env.PRIVATE_KEY],
        },
    },
    solidity: {
        version: "0.8.0",
        settings: {
            optimizer: {
                enabled: true,
                runs: 200,
            },
        },
    },
};

Best Practices

1. Code Quality

• Use latest Solidity version
• Follow style guide
• Document code
• Handle errors

2. Security

• Audit contracts
• Use tested libraries
• Implement safeguards
• Monitor transactions

3. Gas Optimization

• Minimize storage
• Batch operations
• Use efficient types
• Optimize loops

Tools and Resources

1. Development Tools

• Hardhat/Truffle
• Remix IDE
• OpenZeppelin
• Ethers.js

2. Testing Tools

• Mocha/Chai
• Waffle
• Coverage tools
• Gas reporters

3. Security Tools

• Slither
• Mythril
• Echidna
• Manticore

Monitoring and Maintenance

1. Contract Monitoring

• Track events
• Monitor transactions
• Check balances
• Handle errors

2. Upgrades

• Plan upgrades
• Test thoroughly
• Deploy safely
• Verify changes

Remember: Smart contract development requires careful attention to security and best practices.