Hardhat Template

A Hardhat-based template for developing Solidity smart contracts, with sensible defaults.

• Hardhat: compile, run and test smart contracts
• TypeChain: generate TypeScript bindings for smart contracts
• Ethers: renowned Ethereum library and wallet implementation
• Solhint: code linter
• Solcover: code coverage
• Prettier Plugin Solidity: code formatter

Getting Started

Click the Use this template button at the top of the page to create a new repository with this repo as the initial state.

Features

This template builds upon the frameworks and libraries mentioned above, so for details about their specific features, please consult their respective documentations.

For example, for Hardhat, you can refer to the Hardhat Tutorial and the Hardhat Docs. You might be in particular interested in reading the Testing Contracts section.

Sensible Defaults

This template comes with sensible default configurations in the following files:

├── .editorconfig
├── .eslintignore
├── .eslintrc.yml
├── .gitignore
├── .prettierignore
├── .prettierrc.yml
├── .solcover.js
├── .solhint.json
└── hardhat.config.ts

VSCode Integration

This template is IDE agnostic, but for the best user experience, you may want to use it in VSCode alongside Nomic Foundation's Solidity extension.

GitHub Actions

This template comes with GitHub Actions pre-configured. Your contracts will be linted and tested on every push and pull request made to the main branch.

Note though that to make this work, you must use your INFURA_API_KEY and your MNEMONIC as GitHub secrets.

You can edit the CI script in .github/workflows/ci.yml.

Usage

Pre Requisites

Install docker

Install pnpm

Before being able to run any command, you need to create a .env file and set a BIP-39 compatible mnemonic as an environment variable. You can follow the example in .env.example. If you don't already have a mnemonic, you can use this website to generate one.

Then, proceed with installing dependencies:

pnpm install

Start fhEVM

Start a local fhEVM docker container that inlcudes everything needed to deploy FHE encrypted smart contracts

# In one terminal, keep it opened
# The node logs are printed
pnpm fhevm:start

To stop:

pnpm fhevm:stop

Compile

Compile the smart contracts with Hardhat:

pnpm compile

TypeChain

Compile the smart contracts and generate TypeChain bindings:

pnpm typechain

List accounts

From the mnemonic in .env file, list all the derived Ethereum adresses:

pnpm task:accounts

Get some native coins

In order to interact with the blockchain, one need some coins. This command will give coins to the first 5 addresses derived from the mnemonic in .env file.

pnpm fhevm:faucet

To get the first derived address from mnemonic

pnpm task:getEthereumAddress

Deploy

Deploy the ERC20 to local network:

pnpm deploy:contracts

Notes:

Error: cannot get the transaction for EncryptedERC20's previous deployment

One can delete the local folder in deployments:

rm -r deployments/local/

Info: by default, the local network is used

One can change the network, check hardhat config file.

Mint

Run the mint task on the local network:

pnpm task:mint --network local --mint 1000

Test

Run the tests with Hardhat:

pnpm test

Lint Solidity

Lint the Solidity code:

pnpm lint:sol

Lint TypeScript

Lint the TypeScript code:

pnpm lint:ts

Report Gas

See the gas usage per unit test and average gas per method call:

REPORT_GAS=true pnpm test

Clean

Delete the smart contract artifacts, the coverage reports and the Hardhat cache:

pnpm clean

Tasks

Deploy EncryptedERC20

Deploy a new instance of the EncryptedERC20 contract via a task:

pnpm task:deployERC20

Mocked mode

The mocked mode allows faster testing and the ability to analyze coverage of the tests. In this mocked version, encrypted types are not really encrypted, and the tests are run on the original version of the EVM, on a local hardhat network instance. To run the tests in mocked mode, you can use directly the following command:

pnpm test:mock

To analyze the coverage of the tests (in mocked mode necessarily, as this cannot be done on the real fhEVM node), you can use this command :

pnpm coverage:mock

Then open the file coverage/index.html. You can see there which line or branch for each contract which has been covered or missed by your test suite. This allows increased security by pointing out missing branches not covered yet by the current tests.

Notice that, due to intrinsic limitations of the original EVM, the mocked version differ in few corner cases from the real fhEVM, the most important change is the TFHE.isInitialized method which will always return true in the mocked version. Another big difference in mocked mode, compared to the real fhEVM implementation, is that there is no ciphertext verification neither checking that a ciphertext has been honestly obtained (see section 4 of the whitepaper). This means that before deploying to production, developers still need to run the tests with the original fhEVM node, as a final check in non-mocked mode, with pnpm test.

Syntax Highlighting

If you use VSCode, you can get Solidity syntax highlighting with the hardhat-solidity extension.

Using GitPod

GitPod is an open-source developer platform for remote development.

To view the coverage report generated by pnpm coverage, just click Go Live from the status bar to turn the server on/off.

Local development with Docker

Please check the fhevm-go repository to be able to build fhEVM from sources.

License

This project is licensed under MIT.