Brownie is a Python-based development and testing framework for Ethereum smart contracts. It provides support for smart contracts written in Solidity or Vyper, as well as an efficient environment for writing, compiling, deploying, and testing smart contracts on the Ethereum blockchain. In this tutorial, we will create and deploy a simple storage contract written in solidity to the Linea Testnet.

Prerequisites

This tutorial assumes you are familiar with blockchain and solidity basics, and are comfortable using the command terminal.

Create a smart contract

1. First, set up your development environment:

   i. Ensure you have Python and pipx installed on your computer. You can download Python from the official Python website, and you can install pipx by running the following commands in your terminal:

    python3 -m pip install --user pipx
    python3 -m pipx ensurepath
   

   ii. Install Brownie by running the following command in your terminal:

    pipx install eth-brownie
   

   See here for other methods to install brownie

   Once installation is complete, run brownie on your terminal to verify that it worked.

2. Initialize a new Brownie project:

   i. Open your terminal and create a new directory for your Brownie project.

   ii. Navigate to the project's directory.

   iii. Run the following command to initialize a new Brownie project:

    brownie init
   

3. Write your smart contract:

   i. Open your project's directory in your preferred code editor

   ii. Navigate to the contracts directory.

   iii. Create a new Solidity contract file (e.g., MyContract.sol).

   iv. Write your smart contract code using the Solidity syntax. In the example below, we will use a simple storage smart contract written in solidity

    pragma solidity 0.8.17;
   
    // SPDX-License-Identifier: GPL-3.0
   
    contract Storage {}
        uint256 number;
   
        function store(uint num) public {
            number = num;
        }
   
        function retrieve() public view returns (uint){
            return number;
        }
    }
   

4. Set up Infura:

   i. In the root of your project directory, create a file and name it .env.

   ii. Add your WEB3 Infura project ID to the .env file in the following format:

    NETWORK_URL=https://linea-goerli.infura.io/v3/<YOUR-INFURA-PROJECT-ID-HERE>
   

   iii. In the root of your project's directory, create another file and name it brownie.config.yaml.

   iv. In the brownie.config.yaml file, specify the path to the environment variable configuration by adding the following line of code:

    dotenv: .env
   

5. Compile your smart contract:

   i. In your terminal, run the following command to compile your smart contracts:

    brownie compile
   

   Brownie will automatically compile all the contracts in the contracts directory and generate the necessary artifacts.

Deploy a smart contract:

1. Add the Linea network:

   i. In your terminal, run the following command to add Linea to the list of available networks:

    brownie networks add Ethereum Linea host=https://rpc.goerli.linea.build chainid=59140
   

   ii. Confirm you are on the Linea Network by running the following command:

    brownie console --network Linea
   

   Next, input the following options individually:

    network.is_connected()
    network.show_active()
   

2. Add a deployment account:

   You can either add an existing eth account for your smart contract deployment, or create a new account.

   i. To add an existing account, run the following command in your terminal:

    brownie accounts new deployer
   

   You will be prompted to enter the private key for the account you wish to add, and set a password for encryption. Then, your account will be added with the account name: "deployer".

   ii. To create a new account, run the following command in your terminal:

    brownie accounts generate deployer
   

   A mnemonic will be generated, and a new account will be created with the account name: "deployer". Remember to save your mnemonic.

3. Create the corresponding deployment script in the scripts directory and update the deployment script (for example, deploy.py) with your deployment logic.

    #!/usr/bin/3
   
    from brownie import Storage, accounts
   
    def main():
        account = accounts.load('deployer')
        Storage.deploy({'from': account})
   

4. Get Testnet tokens from the Linea Testnet faucet.

5. Run the following command to deploy your smart contract:

    brownie run scripts/deploy.py --network Linea
   

Brownie will now deploy your smart contract to the Linea network.

For additional information, please reference Brownie's documentation.