Proveably Random Raffle Contracts

About

This project is about creating a proveably random smart contract lottery

What we want it to do

1. Users can enter by paying for a ticket

   1. The ticket fees are going to go to the winner during the draw

2. After X period of time, the lottery will automatically draw a winner

   1. And this will be done programmatically

3. Using Chainlink VRF and Chainlink Automation

   1. Chainlink VRF -> Randomness
   2. Chainlink Automation -> Time based trigger

Importing the VRFv2 from Chainlink

To import VRFv2 from Chainlink for use in our Contract, we use this command

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

Next, we go to our foundry.toml file and use remappings to redirect our imports to the location of the relevant file imports on our local machine. This is because sometimes, when we download dependencies on our local machine, the file path may vary from what the github repo is. We remap in foundry.toml using the following command

remappings = ["@chainlink/contracts/src/v0.8/vrf=lib/chainlink-brownie-contracts/contracts/src/v0.8"]

so that the entire foundry.toml file becomes

[profile.default]
src = "src"
out = "out"
libs = ["lib"]
remappings = ["@chainlink/contracts/src/v0.8/vrf=lib/chainlink-brownie-contracts/contracts/src/v0.8"]

Tests

1. We write some deploy scripts

touch ./script/DeployRaffle.s.sol

Because the constructor function of Raffle contract in our Raffle.sol takes input parameters some of which depend on the chain we wish to deploy the contract to, we create a HelperConfig file using the following command

touch ./script/HelperConfig.s.sol

The HelperConfig file is to make our deployment flexible and modular.

We create a mock VRF Coordinator for our Anvil chain by importing the mock script in the chainlink brownie contracts directory thus

import { VRFCoordinatorV2Mock } from "@chainlink-brownie-contracts/contracts/src/v0.8/mocks/VRFCoordinatorV2Mock.sol";

2. We write some tests
   1. Work on local chain
   2. Work on forked Testnet
   3. Work on forked Mainnet

Link Tokens for Chainlink Subscription

The LinkToken.sol file in test/mocks directory was created to enable us fund our subscription. Use the following command to download dependency files for the LinkToken.sol

forge install transmissions11/solmate --no-commit

We then edit remappings in our foundry.toml file to enable us pick the dependency on our local machine without changing the file path on our LinkToken.sol file. Our remappings now become

remappings = ["@chainlink/contracts/src/v0.8/vrf=lib/chainlink-brownie-contracts/contracts/src/v0.8", "@solmate=lib/solmate/src"]

To download dependencies that will enable us add consumer to our subscription, we run the following command

forge install ChainAccelOrg/foundry-devops --no-commit

Unit Test

For our unit test, we create a RaffleTest.t.sol file using the command

mkdir ./test/unit && touch ./test/unit/RaffleTest.t.sol

To run a test, use the following command

forge test

To check the test coverage, use the following command

forge coverage

To check what aspects of our code we have not covered in our test, we run the following command

forge coverage --report debug > coverage.txt

Integration Test

For our integration test, we create a IntegrationTest.t.sol file inside the integration directory using the command

mkdir ./test/integration && touch ./test/integration/IntegrationTest.t.sol

Makefile

The Makefile enables us to name our frequently used commands so that we don't have to always type a lengthy command. We create the Makefile using the command

touch Makefile

In our Makefile, we paste the following lines of code

-include .env

build:; forge build

fund-subscription:
	forge script script/Interactions.s.sol:FundSubscription --rpc-url $(SEPOLIA_RPC_URL) --private-key $(PRIVATE_KEY) --broadcast -vvvv

deploy-sepolia:
	forge script script/DeployRaffle.s.sol:DeployRaffle --rpc-url $(SEPOLIA_RPC_URL) --private-key $(PRIVATE_KEY) --broadcast --verify --etherscan-api-key $(ETHERSCAN_API_KEY) -vvvv

Now, instead of typing it the lengthy command in order to fund our subscription on Chainlink, we use the following command

make fund-subscription

which will call the necessary command and have the task executed.