SmartContract Lottery

A truly random selected lottery smart contract. Players are able to enter the smart contract using their Etheruem rinkeby wallets. The smart contract will randomly select a winner and pay out the prize to the winner.

Prerequisites

Please install or have installed the following:

• nodejs and npm
• python

Installation

1. Install Brownie, if you haven't already. Here is a simple way to install brownie.

python3 -m pip install --user pipx
python3 -m pipx ensurepath
# restart your terminal
pipx install eth-brownie

Or, if that doesn't work, via pip

pip install eth-brownie

2. Download the mix and install dependancies.

brownie bake chainlink-mix
cd chainlink-mix
pip install -r requirements.txt

This will open up a new Chainlink project. Or, you can clone from source:

git clone https://github.com/PatrickAlphaC/chainlink-mix
cd chainlink-mix

Testnet Development

If you want to be able to deploy to testnets, do the following.

With environment variables

Set your WEB3_INFURA_PROJECT_ID, and PRIVATE_KEY environment variables.

You can get a WEB3_INFURA_PROJECT_ID by getting a free trial of Infura. At the moment, it does need to be infura with brownie. If you get lost, you can follow this guide to getting a project key. You can find your PRIVATE_KEY from your ethereum wallet like metamask.

You'll also need testnet rinkeby ETH and LINK. You can get LINK and ETH into your wallet by using the rinkeby faucets located here. If you're new to this, watch this video.

You can add your environment variables to the .env file:

export WEB3_INFURA_PROJECT_ID=<PROJECT_ID>
export PRIVATE_KEY=<PRIVATE_KEY>

AND THEN RUN source .env TO ACTIVATE THE ENV VARIABLES (You'll need to do this everytime you open a new terminal, or learn how to set them easier)

DO NOT SEND YOUR PRIVATE KEY WITH FUNDS IN IT ONTO GITHUB

Without environment variables

Add your account by doing the following:

brownie accounts new <some_name_you_decide>

You'll be prompted to add your private key, and a password. Then, in your code, you'll want to use load instead of add when getting an account.

account = accounts.load("some_name_you_decide")

Then you'll want to add your RPC_URL to the network of choice. For example:

brownie networks modify rinkeby host=https://your_url_here

If the network you want doesn't already exist, see the below section

Otherwise, you can build, test, and deploy on your local environment.

Local Development

For local testing install ganache-cli

npm install -g ganache-cli

or

yarn add global ganache-cli

All the scripts are designed to work locally or on a testnet. You can add a ganache-cli or ganache UI chain like so:

brownie networks add Ethereum ganache host=http://localhost:8545 chainid=1337

And update the brownie config accordingly. There is a deploy_mocks script that will launch and deploy mock Oracles, VRFCoordinators, Link Tokens, and Price Feeds on a Local Blockchain.

Deploy Script

brownie run scripts/deploy_lottery.py

You will need LINK and ETH in your wallet to run this script. Visit the rinkeby faucet to get LINK and ETH.

Testing

There are 2 types of tests in this project.

• unit tests, which run on a local blockchain.
• integration tests, which run on a testnet

To run the unit tests:

brownie test

integration tests:

brownie test --network <network>

For more information on effective testing with Chainlink, check out Testing Smart Contracts

Tests are really robust here! They work for local development and testnets. There are a few key differences between the testnets and the local networks. We utilize mocks so we can work with fake oracles on our testnets.

To test development / local

brownie test

To test mainnet-fork

This will test the same way as local testing, but you will need a connection to a mainnet blockchain (like with the infura environment variable.)

brownie test --network mainnet-fork

To test a testnet

Rinkeby is currently supported

brownie test --network rinkeby

Adding additional Chains

If the blockchain is EVM Compatible, adding new chains can be accomplished by something like:

brownie networks add Ethereum binance-smart-chain host=https://bsc-dataseed1.binance.org chainid=56

or, for a fork:

brownie networks add development binance-fork cmd=ganache-cli host=http://127.0.0.1 fork=https://bsc-dataseed1.binance.org accounts=10 mnemonic=brownie port=8545

Linting

pip install black
pip install autoflake
autoflake --in-place --remove-unused-variables --remove-all-unused-imports -r .
black .

Resources

To get started with Brownie:

• Chainlink Documentation
• Check out the Chainlink documentation to get started from any level of smart contract engineering.
• Check out the other Brownie mixes that can be used as a starting point for your own contracts. They also provide example code to help you get started.
• "Getting Started with Brownie" is a good tutorial to help you familiarize yourself with Brownie.
• For more in-depth information, read the Brownie documentation.

Any questions? Join our Discord