Foundry Smart Contract Lottery

Personal notes

1. This code creates a provably random lottery using Chainlink VRF and Automation
2. Huge shout out to Patrick Collins for making all this!

What we want it to do?

1. Users can pay for a ticket
2. The ticket fees are going to go to the winner
3. After some amount of time, the lottery will auto pick a winner
4. Programatically
5. Use Chainlink VRF (Randomness) & Chainlink Automation (Time-Based Trigger)

Learning to create NatSpec Section in contract (Goes above contract, below pragma)

Error handling

1. doesn't make sense to use require any more bc of gas

2. use revert

3. Created custom gas efficient errors, 1 that takes multiple parameters 2. error My__Error(uint256 someVariable, uint256 anotherVariable); 3. revert My_Error(address(this.balance), anotherVariable.length);

4. name error messages right under contract declaration

   1. error Raffle__NotEnoughEthSent as an example (Two underscores after contract name then error)

Enums

1. An enum (short for "enumeration") is a user-defined data type that consists of a set of named values, called elements or members, representing distinct constants. It is used to define variables that can only hold one of the predefined values, improving code readability and reducing errors.

Constructor and HelperConfig script

1. Raffle.sol has a robust constructor ready to go for any chain deployment, simply add a new config function in HelperConfig

Create Chainlink VRF Subscription

https://vrf.chain.link/sepolia/new

1. Connect Wallet and approve transaction
2. Get test LINK and ETH
3. Create Subscription using Metamask
4. Fund Subscription

Create Chainlink Automation Account

https://automation.chain.link/

1. Register New Upkeep
2. Use custom logic
3. Fill in blanks

State Variables

1. cheaper to make all upper case (goes right under error message or contract name), add getter functions

Modulo function is goofy

1. It works more like take the first set of numbers and see what is left over 2334502 % 10 is just the 2 at the end bc it's what is left over

CEI: Checks Effects and Interactions

1. do checks (require if--> error) early in function (more gas efficient)
2. do effect after checks
3. interactions with other contracts come later
   1. events come before interactions

Chainlink upKeep

1. we don't have to call the pick winner function bc Chainlink nodes will do that using automation.

Script

1. Designed to deploy the raffle.sol for any chain setup in the config file

Testing

1. Assess, Act, Assert

Cyfrin ReadMe

This is a section from the Cyfrin Foundry Solidity Course.

⭐️ (3:04:09) | Lesson 9: Foundry Smart Contract Lottery

• Foundry Smart Contract Lottery
  • Personal notes
  • What we want it to do?
  • Learning to create NatSpec Section in contract (Goes above contract, below pragma)
  • Error handling
  • Enums
  • Constructor and HelperConfig script
  • Create Chainlink VRF Subscription
  • Create Chainlink Automation Account
  • State Variables
  • Modulo function is goofy
  • CEI: Checks Effects and Interactions
  • Chainlink upKeep
  • Script
  • Testing
• Cyfrin ReadMe
• Getting Started
  • Requirements
  • Quickstart
• Usage
  • Start a local node
  • Library
  • Deploy
  • Deploy - Other Network
  • Testing
    • Test Coverage
• Deployment to a testnet or mainnet
  • Scripts
  • Estimate gas
• Formatting

Getting Started

Requirements

• git
  • You'll know you did it right if you can run git --version and you see a response like git version x.x.x
• foundry
  • You'll know you did it right if you can run forge --version and you see a response like forge 0.2.0 (816e00b 2023-03-16T00:05:26.396218Z)

Quickstart

git clone https://github.com/CPix18/FoundrySmartLottery
cd FoundrySmartLottery
forge build

Usage

Start a local node

make anvil

Library

If you're having a hard time installing the chainlink library, you can optionally run this command.

forge install smartcontractkit/chainlink-brownie-contracts@0.6.1 --no-commit

Deploy

This will default to your local node. You need to have it running in another terminal in order for it to deploy.

make deploy

Deploy - Other Network

See below

Testing

We talk about 4 test tiers in the video.

1. Unit
2. Integration
3. Forked
4. Staging

This repo we cover #1 and #3.

forge test

or

forge test --fork-url $SEPOLIA_RPC_URL

Test Coverage

forge coverage

Deployment to a testnet or mainnet

1. Setup environment variables

You'll want to set your SEPOLIA_RPC_URL and PRIVATE_KEY as environment variables. You can add them to a .env file, similar to what you see in .env.example.

• PRIVATE_KEY: The private key of your account (like from metamask). NOTE: FOR DEVELOPMENT, PLEASE USE A KEY THAT DOESN'T HAVE ANY REAL FUNDS ASSOCIATED WITH IT.
  • You can learn how to export it here.
• SEPOLIA_RPC_URL: This is url of the sepolia testnet node you're working with. You can get setup with one for free from Alchemy

Optionally, add your ETHERSCAN_API_KEY if you want to verify your contract on Etherscan.

1. Get testnet ETH

Head over to faucets.chain.link and get some testnet ETH. You should see the ETH show up in your metamask.

2. Deploy

make deploy ARGS="--network sepolia"

This will setup a ChainlinkVRF Subscription for you. If you already have one, update it in the scripts/HelperConfig.s.sol file. It will also automatically add your contract as a consumer.

3. Register a Chainlink Automation Upkeep

You can follow the documentation if you get lost.

Go to automation.chain.link and register a new upkeep. Choose Custom logic as your trigger mechanism for automation. Your UI will look something like this once completed:

Scripts

After deploying to a testnet or local net, you can run the scripts.

Using cast deployed locally example:

cast send <RAFFLE_CONTRACT_ADDRESS> "enterRaffle()" --value 0.1ether --private-key <PRIVATE_KEY> --rpc-url $SEPOLIA_RPC_URL

or, to create a ChainlinkVRF Subscription:

make createSubscription ARGS="--network sepolia"

Estimate gas

You can estimate how much gas things cost by running:

forge snapshot

And you'll see an output file called .gas-snapshot

Formatting

To run code formatting:

forge fmt

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ETH/Arbitrum/Optimism/Polygon/etc Address: 0x75C875c4b81D792797c6ccCe724c03FE8d31FE0e