Tokenizer (42) - Goodies42

ERC20 project developed as part of the 42 school curriculum.

Summary

Goodies42 (GDS42) is a utility token used to reward students and purchase goodies through a shop contract.

• Name: Goodies42
• Symbol: GDS42
• Decimals: 18 (fixed)
• Standard: ERC20 (IERC20Metadata)
• Target blockchain: Sepolia

Project Structure (assignment-compliant)

Goodies42
├── code/   # token source code and tests
│   ├── contracts/
│   │   └── Goodies42.sol
│   └── test/
│       └── Goodies42.test.ts
├── deployment/   # deployment files
│   └── Modules/
│       └── Goodies42.ts
├── documentation/   # project docs
│   ├── WHITEPAPER_FR.md
│   └── WHITEPAPER_US.md
├── Makefile
├── README.md
├── README_FR.md
└── config files (json, ts, env, gitignore)

Configuration files remain at the repository root (hardhat.config.ts, package.json, tsconfig.json) to keep standard Hardhat conventions.

Contracts

code/contracts/Goodies42.sol

Implements the core ERC20 functions:

• transfer
• approve
• transferFrom
• mint (owner only)

Security/ownership:

• onlyOwner on sensitive functions
• 2-step ownership transfer: transferOwnership then acceptOwnership
• ownership can be transferred to a multisig

code/contracts/Goodies42Shop.sol

Handles item purchases through buy:

• on-chain price check via itemPrice[itemId]
• bonus access (LotteryAccess) if the answer is correct
• otherwise transfers token payment to the shop treasury
• max LotteryAccess per user: 3
• admin withdrawal available via withdrawTokens

Purchase Flow (student wallet)

Standard dApp flow:

1. Student connects wallet (MetaMask) to the dApp.
2. dApp reads on-chain price with itemPrice(itemId).
3. dApp checks token allowance for Goodies42Shop.
4. If allowance is too low, dApp requests approve(shopAddress, price).
5. Student confirms the approve transaction in wallet.
6. dApp then sends buy(itemId, answer).
7. Student confirms the buy transaction in wallet.
8. Contract applies the rule:
   • valid bonus: no token payment, LotteryAccess is consumed
   • otherwise: transferFrom(student, shop, price)
9. Backend can confirm purchase by reading the on-chain ItemPurchased event.

Commands

Via Makefile:

make install
make compile
make test
make node
make deploy-local
make deploy-sepolia

Why an RPC Provider Is Required

To deploy on Sepolia, Hardhat must connect to an Ethereum node through an RPC URL.

• Target blockchain is Sepolia, but access is through an RPC provider (Alchemy, Infura, QuickNode, etc.)
• Without a valid RPC URL, the project cannot read chain state or broadcast deployment transactions
• Public endpoints may exist, but they are often rate-limited or unstable

Required variables:

• SEPOLIA_RPC_URL: HTTP URL of the Sepolia RPC provider
• PRIVATE_KEY: private key of the deployment wallet (dedicated testnet wallet)

Prepare Sepolia environment:

cp .env.example .env
# then fill SEPOLIA_RPC_URL and PRIVATE_KEY in .env

Without Makefile:

npx hardhat compile
npx hardhat test
npx hardhat ignition deploy ./deployment/ignition/modules/Goodies42Core.ts --network localhost
npx hardhat ignition deploy ./deployment/ignition/modules/Goodies42Core.ts --network sepolia

Public Deployment (to complete)

• Goodies42 (Sepolia): 0xaDf4D6A3889962F5EF5658a813C75f7c922334ED
• Goodies42Shop (Sepolia): 0x15a97d74EC9aE403E791B9A59F8656dE8a6Cc750
• Etherscan link: https://sepolia.etherscan.io/address/0x15a97d74EC9aE403E791B9A59F8656dE8a6Cc750#code

Whitepapers

See WHITEPAPER FR and WHITEPAPER US.