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ERC-20 Token Hardhat Example

A complete ERC-20 token implementation using Hardhat v2, featuring modern development tools and best practices for deploying to the Polkadot testnet.

Overview

This project demonstrates how to create, deploy, and test an ERC-20 token contract using Hardhat. The token implementation includes standard ERC-20 functionality plus minting capabilities and owner controls.

Token Features

The MyToken contract implements:

  • ERC-20 Standard: Full compliance with the ERC-20 token standard
  • Minting: Owner can mint new tokens to any address
  • ERC-20 Permit: Gasless approvals using cryptographic signatures
  • Ownable: Access control with owner-only functions
  • OpenZeppelin: Built using audited, battle-tested contracts

Token Details

  • Name: MyToken
  • Symbol: MTK
  • Decimals: 18 (standard)
  • Total Supply: Controlled by owner (no initial supply, mint as needed)

Project Structure

erc20-hardhat/
├── contracts/
│   └── MyToken.sol          # Main ERC-20 token contract
├── test/
│   └── MyToken.test.ts      # Mocha/Chai tests
├── ignition/
│   └── modules/
│       └── MyToken.ts       # Deployment configuration
├── artifacts/               # Compiled contracts (auto-generated)
├── cache/                   # Hardhat cache (auto-generated)
├── typechain-types/         # TypeScript types (auto-generated)
├── hardhat.config.ts        # Hardhat configuration
├── package.json             # Project dependencies
├── tsconfig.json            # TypeScript configuration
└── README.md               # This file

Quick Start

1. Install Dependencies

npm install

2. Compile Contracts

npx hardhat compile

3. Run Tests

Run tests against the Polkadot testnet:

npm run test:polkadot

Or run tests on the default Hardhat network:

npm test

4. Deploy Locally

Deploy to Hardhat's built-in network:

npx hardhat ignition deploy ignition/modules/MyToken.ts

Deployment

Local Development

The project is configured to work with Hardhat's built-in network by default. Simply run:

npx hardhat ignition deploy ignition/modules/MyToken.ts

This will:

  1. Deploy the MyToken contract
  2. Set the first account as the owner
  3. Mint 5 MTK tokens to the owner address

Polkadot Testnet

To deploy to the Polkadot testnet, you need an account with funds to send the transaction. The Hardhat configuration uses Configuration Variables for secure private key management.

Setup Configuration Variables

  1. Set your private key:

    npx hardhat vars set TESTNET_PRIVATE_KEY

    You'll be prompted to enter your private key securely. The value is encrypted and stored locally.

  2. (Optional) Set a custom network URL:

    npx hardhat vars set TESTNET_URL

    If not set, defaults to http://127.0.0.1:8545

  3. Verify your configuration:

    npx hardhat vars list

Deploy to Testnet

npx hardhat ignition deploy ignition/modules/MyToken.ts --network polkadotTestnet

Note: If you get an error about pending transactions, wait a minute for previous transactions to be confirmed (they need 5 confirmations), then try again.

Configuration

Configuration Variables

Hardhat Configuration Variables provide secure, encrypted storage for sensitive data:

  • TESTNET_PRIVATE_KEY: Your private key for deployment (required)
  • TESTNET_URL: Custom RPC endpoint (optional, defaults to http://127.0.0.1:8545)

Useful Commands:

# Set a variable (will prompt for value)
npx hardhat vars set TESTNET_PRIVATE_KEY

# List all variables
npx hardhat vars list

# View a variable
npx hardhat vars get TESTNET_PRIVATE_KEY

# Delete a variable
npx hardhat vars delete TESTNET_PRIVATE_KEY

# See storage location
npx hardhat vars path

Network Configuration

The project includes the following networks:

  • hardhat: Built-in Hardhat network (default)
  • polkadotTestnet: Local Polkadot testnet node at http://127.0.0.1:8545

Contract Interaction Examples

Using Hardhat Console

npx hardhat console --network localhost
// Get the deployed contract
const MyToken = await ethers.getContractFactory("MyToken");
const token = await MyToken.attach("DEPLOYED_CONTRACT_ADDRESS");

// Check token details
await token.name();        // "MyToken"
await token.symbol();      // "MTK"
await token.decimals();    // 18

// Mint tokens (only owner)
await token.mint("0x...", ethers.parseEther("100"));

// Check balance
await token.balanceOf("0x...");

Development Features

This project uses modern Ethereum development practices:

  • Hardhat v2: Stable, production-ready development environment
  • TypeScript: Full type safety throughout the project
  • Ethers v6: Modern Ethereum library for contract interactions
  • Mocha + Chai: Robust testing framework
  • TypeChain: Auto-generated TypeScript types for contracts
  • OpenZeppelin: Industry-standard smart contract libraries
  • Hardhat Ignition: Declarative deployment system
  • Configuration Variables: Secure, encrypted key management

Testing

The project includes comprehensive TypeScript tests using Mocha and Chai:

  • Test File: test/MyToken.test.ts
  • Framework: Mocha with Chai assertions
  • Features Tested:
    • Contract deployment
    • Token name, symbol, and decimals
    • Owner assignment
    • Minting functionality
    • Balance tracking
    • Total supply updates

Run tests:

# Against Polkadot testnet
npm run test:polkadot

# On Hardhat network
npm test

Security Considerations

  • The contract uses OpenZeppelin's audited implementations
  • Owner privileges are clearly defined and limited to minting
  • ERC-20 Permit reduces gas costs and improves UX for approvals
  • All standard ERC-20 security patterns are implemented

Learn More

Contributing

Contributions are welcome! Please ensure:

  1. All tests pass
  2. Code follows the existing style
  3. New features include appropriate tests
  4. Documentation is updated as needed

License

This project is licensed under the MIT License.