Awesome
<br/> <p align="center"> <a href="https://chain.link" target="_blank"> <img src="./box-img-lg.png" width="225" alt="Chainlink Hardhat logo"> </a> </p> <br/>Tip
Please be attention that Chainlink Any API is removed from this starter kit because Chainlink Any API is currently replaced by Chainlink Functions. Please find the starter kit for Chainlink Functions here
- Chainlink Hardhat Starter Kit
- Getting Started
- Usage
- Test
- Interacting with Deployed Contracts
- Linting
- Code Formatting
- Estimating Gas
- Code Coverage
- Fuzzing
- Contributing
- Thank You!
Chainlink Hardhat Starter Kit
Implementation of the following 3 Chainlink features using the Hardhat development environment:
For Chainlink Functions please go to these tarter kits: Hardhat | Foundry (coming soon)
For Chainlink CCIP (Cross Chain Interoperability Prototocol) please go to these starter kits: Hardhat | Foundry
Getting Started
It's recommended that you've gone through the hardhat getting started documentation before proceeding here.
Requirements
- git
- You'll know you did it right if you can run
git --version
and see a response likegit version x.x.x
- You'll know you did it right if you can run
- Nodejs
- You'll know you've installed nodejs right if you can run:
node --version
and get an output like:vx.x.x
- You'll know you've installed nodejs right if you can run:
- Yarn instead of
npm
- You'll know you've installed yarn right if you can run:
yarn --version
And get an output like:x.x.x
- You might need to install it with npm
- You'll know you've installed yarn right if you can run:
If you're familiar with
npx
andnpm
instead ofyarn
, you can usenpx
for execution andnpm
for installing dependencies.
Quickstart
- Clone and install dependencies
After installing all the requirements, run the following:
git clone https://github.com/smartcontractkit/hardhat-starter-kit/
cd hardhat-starter-kit
Then:
npm install
The recommendation is to use npm 7 or later. If you are using an older version of npm, you'll also need to install all the packages used by the toolbox.
npm install --save-dev @nomicfoundation/hardhat-toolbox @nomicfoundation/hardhat-network-helpers @nomicfoundation/hardhat-chai-matchers @nomiclabs/hardhat-ethers @nomiclabs/hardhat-etherscan chai ethers hardhat-gas-reporter solidity-coverage @typechain/hardhat typechain @typechain/ethers-v5 @ethersproject/abi @ethersproject/providers
That's also the case if you are using yarn.
yarn add --dev @nomicfoundation/hardhat-toolbox @nomicfoundation/hardhat-network-helpers @nomicfoundation/hardhat-chai-matchers @nomiclabs/hardhat-ethers @nomiclabs/hardhat-etherscan chai ethers hardhat-gas-reporter solidity-coverage @typechain/hardhat typechain @typechain/ethers-v5 @ethersproject/abi @ethersproject/providers
- You can now do stuff!
npx hardhat test
or
npm run test
or
yarn test
Typescript
To use typescript, run:
git checkout typescript
npm install
Usage
If you run npx hardhat --help
you'll get an output of all the tasks you can run.
Deploying Contracts
npm run deploy
This will deploy your contracts to a local network. Additionally, if on a local network, it will deploy mock Chainlink contracts for you to interact with. If you'd like to interact with your deployed contracts, skip down to Interacting with Deployed Contracts.
Run a Local Network
One of the best ways to test and interact with smart contracts is by using a local network. To run a local network with all your contracts in it, execute the following command:
npx hardhat node
You'll get a local blockchain, private keys, contracts deployed (from the deployment
folder scripts), and an endpoint to potentially add to an EVM wallet.
Using a Testnet or Live Network (like Mainnet or Polygon)
In your hardhat.config.js
you'll see section like:
module.exports = {
defaultNetwork: "hardhat",
networks: {
This section of the file is where you define which networks you want to interact with. You can read more about that whole file in the hardhat documentation.
To interact with a live or test network, you'll need:
- An rpc URL
- A Private Key
- ETH & LINK token (either testnet or real)
Let's look at an example of setting these up using the Sepolia testnet.
Sepolia Ethereum Testnet Setup
First, we will need to set environment variables. We can do so by setting them in our .env
file (create it if it's not there). You can also read more about environment variables from the linked twilio blog. You'll find a sample of what this file will look like in .env.example
IMPORTANT: MAKE SURE YOU'D DON'T EXPOSE THE KEYS YOU PUT IN THIS
.env
FILE. By that, I mean don't push them to a public repo, and please try to keep them keys you use in development not associated with any real funds.
- Set your
SEPOLIA_RPC_URL
environment variable.
You can get one for free from Alchemy, Infura, or Moralis. This is your connection to the blockchain.
- Set your
PRIVATE_KEY
environment variable.
This is your private key from your wallet, ie MetaMask. This is needed for deploying contracts to public networks. You can optionally set your MNEMONIC
environment variable instead with some changes to the hardhat.config.js
.
WARNING
When developing, it's best practice to use a Metamask that isn't associated with any real money. A good way to do this is to make a new browser profile (on Chrome, Brave, Firefox, etc) and install Metamask on that browser, and never send this wallet money.
Don't commit and push any changes to .env files that may contain sensitive information, such as a private key! If this information reaches a public GitHub repository, someone can use it to check if you have any Mainnet funds in that wallet address, and steal them!
.env
example:
SEPOLIA_RPC_URL='https://sepolia.infura.io/v3/asdfadsfafdadf'
PRIVATE_KEY='abcdef'
bash
example:
export SEPOLIA_RPC_URL='https://sepolia.infura.io/v3/asdfadsfafdadf'
export PRIVATE_KEY='abcdef'
You can also use a
MNEMONIC
instead of aPRIVATE_KEY
environment variable by uncommenting the section in thehardhat.config.js
, and commenting out thePRIVATE_KEY
line. However this is not recommended.
For other networks like mainnet and polygon, you can use different environment variables for your RPC URL and your private key. See the hardhat.config.js
to learn more.
- Get some Sepolia Testnet ETH and LINK
Head over to the Chainlink faucets and get some ETH and LINK. Please follow the chainlink documentation if unfamiliar.
- Create VRF V2 subscription
Head over to VRF Subscription Page and create the new subscription. Save your subscription ID and put it in helper-hardhat-config.js
file as subscriptionId
- Running commands
You should now be all setup! You can run any command and just pass the --network sepolia
now!
To deploy contracts:
npm run deploy --network sepolia
To run staging testnet tests
npm run test-staging
Forking
If you would like to run tests on a forked network, follow these steps:
- Set a
MAINNET_RPC_URL
environment variable that connects to the mainnet. - Choose a block number to select a state of the network you are forking and set it as
FORKING_BLOCK_NUMBER
environment variable. If ignored, it will use the latest block each time which can lead to test inconsistency. - Set
enabled
flag totrue
/false
to enable/disable forking feature
forking: {
url: MAINNET_RPC_URL,
blockNumber: FORKING_BLOCK_NUMBER,
enabled: false,
}
Test
Tests are located in the test directory, and are split between unit tests and staging/testnet tests. Unit tests should only be run on local environments, and staging tests should only run on live environments.
To run unit tests:
npx hardhat test
or
npm run test
or
yarn test
To run staging tests on Sepolia network:
npx hardhat test --network sepolia
or
npm run test-staging
Performance optimizations
Since all tests are written in a way to be independent from each other, you can save time by running them in parallel. Make sure that AUTO_FUND=false
inside .env
file. There are some limitations with parallel testing, read more about them here
To run tests in parallel:
npx hardhat test --parallel
or
npm run test --parallel
Interacting with Deployed Contracts
After deploying your contracts, the deployment output will give you the contract addresses as they are deployed. You can then use these contract addresses in conjunction with Hardhat tasks to perform operations on each contract.
Chainlink Price Feeds
The Price Feeds consumer contract has one task, to read the latest price of a specified price feed contract
npx hardhat read-price-feed --contract insert-contract-address-here --network network
VRF Get a random number
The VRFConsumer contract has two tasks, one to request a random number, and one to read the result of the random number request. As explained in the developer documentation, there are two methods:
Read the docs first to understand which method is the most suitable for your use case.
VRF Subscription method
To start, go to VRF Subscription Page and create the new subscription. Save your subscription ID and put it in helper-hardhat-config.js
file as subscriptionId
:
5: {
// rest of the config
subscriptionId: "777"
}
Then, deploy your VRF V2 contract consumer to the network of your recent subscription using subscription id as constructor argument.
npm run deploy --network network
Finally, you need to go to your subscription page one more time and add the address of deployed contract as a new consumer. Once that's done, you can perform a VRF request with the request-random-number task:
npx hardhat request-random-number --contract insert-contract-address-here --network network
Once you have successfully made a request for a random number, you can see the result via the read-random-number task:
npx hardhat read-random-number --contract insert-contract-address-here --network network
VRF Direct Funding method
Deploy your VRF V2 contract consumer to the network.
npm run deploy --network network
or (if you are using yarn)
yarn deploy --network network
Now you have to fund your consumer contract with LINK tokens:
npx hardhat transfer-link --recipient insert-contract-address-here --amount insert-amount-in-juels-here --network network
Once that's done, you can perform a VRF request with the request-random-number task:
npx hardhat request-random-number-direct-funding --callbackgaslimit insert-callback-gas-limit-here --requestconfirmations insert-request-confirmations-here --numwords insert-number-words-here --contract insert-contract-address-here --network network
Once you have successfully made a request for a random number, you can see the result via the read-random-number task:
npx hardhat read-random-number-direct-funding --contract insert-contract-address-here --network network
Automation
The AutomationCounter contract is a simple Chainlink Automation enabled contract that simply maintains a counter variable that gets incremented each time the performUpkeep task is performed by a Chainlink Automation. Once the contract is deployed, you should head to https://automation.chain.link/ to register it for upkeeps, then you can use the task below to view the counter variable that gets incremented by Chainlink Automation
npx hardhat read-automation-counter --contract insert-contract-address-here --network network
Verify on Etherscan
You'll need an ETHERSCAN_API_KEY
environment variable. You can get one from the Etherscan API site.. If you have it set, your deploy script will try to verify them by default, but if you want to verify any manually, you can run:
npx hardhat verify --network <NETWORK> <CONTRACT_ADDRESS> <CONSTRUCTOR_PARAMETERS>
example:
npx hardhat verify --network sepolia 0x9279791897f112a41FfDa267ff7DbBC46b96c296 "0x694AA1769357215DE4FAC081bf1f309aDC325306"
Linting
This will lint your smart contracts.
npm run lint:fix
Code Formatting
This will format both your javascript and solidity to look nicer.
npm run format
Estimating Gas
To estimate gas, just set a REPORT_GAS
environment variable to true, and then run:
npx hardhat test
If you'd like to see the gas prices in USD or other currency, add a COINMARKETCAP_API_KEY
from Coinmarketcap.
Code coverage
To see a measure in percent of the degree to which the smart contract source code is executed when a particular test suite is run, type
npm run coverage
Fuzzing
We are going to use Echidna as a Fuzz testing tool. You need to have Docker installed with at least 8GB virtual memory allocated (To update this parameter go to Settings->Resources->Advanced->Memory).
To start Echidna instance run
npm run fuzzing
If you are using it for the first time, you will need to wait for Docker to download eth-security-toolbox image for us.
To start Fuzzing run
echidna-test /src/contracts/test/fuzzing/AutomationCounterEchidnaTest.sol --contract AutomationCounterEchidnaTest --config /src/contracts/test/fuzzing/config.yaml
To exit Echidna type
exit
Contributing
Contributions are always welcome! Open a PR or an issue!