Hardhat Smart Contract Lottery (Raffle)

Quickstart

Clone the repo

git clone https://github.com/0xSanyam/Smart-Contract-Lottery.git

Typescript

If you want to get to typescript and you cloned the javascript version, just run:

git checkout typescript

Usage

Deploy:

yarn hardhat deploy

Testing

yarn hardhat test

Test Coverage

yarn hardhat coverage

Deployment to a testnet or mainnet

1. Setup environment variables

   You'll want to set your POLYGON_RPC_URL and PRIVATE_KEY as environment variables. You can add them to a .env file.

   • PRIVATE_KEY: The private key of your account (like from metamask).

   • POLYGON_RPC_URL: This is url of the rinkeby testnet node you're working with. You can get one for free from Alchemy

2. Get testnet ETH

   Go to faucets.chain.link and get some testnet ETH & LINK. You should see the ETH and LINK show up in your metamask. You can read more on setting up your wallet with LINK.

3. Setup a Chainlink VRF Subscription ID

   Head over to vrf.chain.link and setup a new subscription, and get a subscription Id. You can reuse an old subscription if you already have one.

You should leave this step with:

1. A subscription ID
2. Your subscription should be funded with LINK
3. Deploy

In your hardhat-helper.js add your subscription Id under the section of the chainId you're using (that is, if you're deploying to rinkeby, add your subscription Id in the subscriptionId field under the 80001 section.)

Then run:

yarn hardhat deploy --network matic

And copy / remember the contract address.

4. Add your contract address as a Chainlink VRF Consumer

   Go back to vrf.chain.link and under your subscription, click Add consumer and add your contract address. You should also fund the contract with a minimum of 3 LINK.

   

5. Register a Chainlink Keepers Upkeep

   Go to keepers.chain.link and register a new upkeep.

   

6. Enter in the lottery!

   Your contract is now setup to be a tamper proof autonomous verifiably random lottery.

   Enter the lottery by running:

   yarn hardhat run scripts/enter.js --network matic
   

Estimate gas cost in INR

To get the INR estimation of gas cost, you'll need a COINMARKETCAP_API_KEY environment variable. You can get one for free from CoinMarketCap.

Just note, everytime you run your tests it will use an API call, so it might make sense to have coinmarketcap disabled until you need it. You can disable it by just commenting the line out.

Verify on polygonscan

If you deploy to a testnet or mainnet, you can verify it if you get an API Key from PolygonScan and set it as an environemnt variable named POLYGONSCAN_API_KEY. You can add it into your .env file.

In it's current state, if you have your api key set, it will auto verify the contracts!

However, you can manual verify with:

yarn hardhat verify --constructor-args arguments DEPLOYED_CONTRACT_ADDRESS