🪙 MyToken – Custom ERC20 Implementation

This project is a custom-built, security-focused implementation of an ERC20 token, created from scratch without using any external libraries like OpenZeppelin. It's fully tested and achieves 100% test coverage using Foundry's forge coverage.

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🚀 Key Features

• ✅ Built fully from scratch (no external dependencies)
• 🔐 Secure error handling with custom errors
• 🧪 100% test coverage with Foundry
• 👨‍💻 Owner-only mint functionality
• 🔥 Public burn functionality
• 📥 approve, transferFrom, increaseAllowance, decreaseAllowance support
• 🚫 Custom reverts for cleaner gas-efficient error messages
• 🧱 MAX_SUPPLY constraint enforced

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🔍 Contract Overview

Function	Description
constructor	Initializes token with name, symbol, decimals, and initial supply
mint()	Owner-only function to mint tokens without exceeding MAX_SUPPLY
burn()	Burns caller's tokens
transfer()	Transfers tokens to another address
approve()	Approves a spender to spend on caller's behalf
transferFrom()	Allows spending tokens via allowance
increaseAllowance()	Safely increases allowance for a spender
decreaseAllowance()	Safely decreases allowance for a spender

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🛡️ Custom Errors

Custom errors are used instead of revert strings to save gas and improve readability:

• MyToken__NotOwner()
• MyToken__MaxSupplyExceeds()
• MyToken__NotEnoughTokens()
• MyToken__InvalidAddress()
• MyToken__AllowanceExceeds()
• MyToken__NotEnoughAllowance()

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🔧 Tech Stack

• Solidity: ^0.8.24
• Framework: Foundry
• Test Coverage: 100% via forge coverage

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✅ Getting Started

🔗 Clone Repo

git clone https://github.com/Eunum56/foundry-ERC20
cd foundry-ERC20

🧪 Install & Run Tests

forge install
forge build
forge test

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Contributing

Feel free to fork this repository and submit pull requests. If you have suggestions or encounter any bugs, please open an issue in the GitHub repository.

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Built with ❤️, tested with 🧪, and deployed with 💪