Note

If you wish to suggest changes on this document, please open a PR on the Foundry Starter Kit Repository

Rootstock Foundry Starter Kit

Whether you’re a seasoned developer or just starting your journey into smart contract development, the foundry starter kit provides a solid foundation for building decentralized applications (dApps) on the Rootstock network.

Rootstock is fully EVM (Ethereum Virtual Machine) compatible. It brings the power of smart contracts to Bitcoin, allowing developers to leverage Bitcoin’s security while benefiting from Ethereum’s ecosystem.

In this tutorial, you'll learn how to set up your Foundry development environment, connect to a Rootstock network, write and test smart contracts, deploy them to the Rootstock blockchain, and interact with them. We'll guide you through every step, from installation to minting your first token.

Prerequisites

Before starting the dApp, make sure to have the following prerequisites:

1. Familiarity with Smart Contracts:

   • If you’re new to smart contracts, consider learning the basics. Understanding how smart contracts work will enhance your experience with Rootstock development.

2. Foundry installation using Foundryup:

• To install, visit the official Foundry documentation for more information.
• Foundryup is the official installer for the Foundry toolchain. You can learn more about it in the Foundryup README.
• If you encounter any issues during installation, refer to the Foundryup FAQ for assistance.
• Precompiled binaries can be downloaded from the Foundry GitHub releases page. For easier management, we recommend using Foundryup.

To install Foundry in your system, run the following command:

curl -L https://foundry.paradigm.xyz | bash

This will install Foundryup. Follow the on-screen instructions, and the foundryup command will be available via the CLI.

Running foundryup automatically installs the latest (nightly) versions of the precompiled binaries: forge, cast, anvil, and chisel. For additional options, such as installing a specific version or commit, run foundryup --help.

Using Windows

If you’re using Windows, you’ll need to install and use Git BASH or WSL as your terminal, since Foundryup currently doesn’t support Powershell or Command Prompt (Cmd).

3. Basic Knowledge of Foundry:

• Familiarity with Foundry's core concepts and functionalities is recommended. If you're new to Foundry, refer to the Rootstock Foundry Guide.

Rootstock Blockchain Developer Course

Learn how to write, test, secure, deploy and verify smart contracts on the Rootstock blockchain network. Enroll for the Rootstock Blockchain Developer Course.

Setting Up the Sample dApp

Clone the Repository

Open your terminal or command prompt and run the following command to clone the repository from GitHub:

git clone https://github.com/rsksmart/rootstock-foundry-starterkit.git

Install Dependencies

Navigate to the cloned repository folder:

cd rootstock-foundry-starterkit

Install all required dependencies using forge:

forge install OpenZeppelin/openzeppelin-contracts

The project uses remappings in foundry.toml for clean import paths. This allows you to use @openzeppelin/contracts/ imports directly in your Solidity files.

Add Rootstock Testnet and Mainnet RPC URLs

This section will walk you through adding Rootstock Testnet and Mainnet RPC URLs to your development environment. These URLs are essential for connecting your application to the Rootstock network and interacting with smart contracts.

There are two ways to obtain RPC URLs:

Using Public RPC URLs

• Visit the MetaMask Integration on the Rootstock DevPortal. This guide provides instructions on setting up MetaMask for Rootstock. While following these steps, pay close attention to the sections on adding custom networks. You'll find the RPC URLs for Rootstock Testnet and Mainnet listed.

Using RPC API

• Create an account on the Rootstock RPC API. Once logged in, navigate to your dashboard and copy the API Key.

Adding environment variables to your project

After obtaining the RPC URLs, create a file named .env in your project's root directory /.env at the same level of .env.example file (important: this file should not be committed to version control). Add the next environment variable to the .env file:

PRIVATE_KEY: Your private key (e.g., from your Metamask account details).

Tip

Ensure the private key copied starts with 0x...

Running tests on an ERC20 Token Contract

This section runs tests on an ERC20 token contract (fungible token), this is done according to the script located at test/Erc20Token.t.sol. It does test deployment, minting, and transfer of tokens.

For this, run the next forge command:

forge test

It should return an output similar to the following:

Compiler run successful!

Ran 2 tests for test/Erc20Token.t.sol:ERC20TokenTest
[PASS] testInitialSupply() (gas: 9849)
[PASS] testTransfer() (gas: 43809)
Suite result: ok. 2 passed; 0 failed; 0 skipped; finished in 8.73ms (1.51ms CPU time)

Ran 1 test suite in 143.90ms (8.73ms CPU time): 2 tests passed, 0 failed, 0 skipped (2 total tests)

NOTE: If you need additional tests, or want to go deep on this step, visit the Foundry Tests Documentation.

Deploying an ERC20 Token Contract

This section deploys an ERC20 token contract (fungible token) on the Rootstock network. This contract is located at src/Erc20Token.sol file, it uses the script located at script/Deploy.s.sol for this operation.

Run the following command, replacing https://public-node.testnet.rsk.co with either rskTestnet or rskMainnet rpc url if you have the testnet and mainnet environments configured for your desired deployment environment, for this guide, we will use the public node url:

forge script script/Deploy.s.sol --rpc-url https://public-node.testnet.rsk.co --broadcast --evm-version cancun

• You can remove the --broadcast flag if you want to simulate the transaction without broadcasting it. :::

If you encounter an error such as Transaction dropped from the mempool: <tx-id> or transaction not completed, check the tx-id in the explorer. The transaction may have been successful but the error is still within the logs. See the mainnet and testnet explorers for more info.

Also you can see the transaction registry locally, by checking the folder broadcast/Deploy.s.sol/ and opening the file called run-latest.json. See the field called contractAddress which contains the new address deployed for the ERC20 smart contract.

The result should look like this:

## Setting up 1 EVM.

==========================

Chain 31

Estimated gas price: 0.004445349 gwei

Estimated total gas used for script: 1224342

Estimated amount required: 0.000005442627485358 tRBTC

==========================

##### rsk-testnet
✅  [Success] Hash: 0x90aa81ad4e023ce4a2ab964b5aad7f425079d8fd717ec73fd76434ca85d10bb1
Contract Address: 0xF85524C329337Ae5D240F194454c691383ebCF86
Block: 6610544
Paid: 0.000004152853926498 tRBTC (934202 gas * 0.004445349 gwei)

✅ Sequence #1 on rsk-testnet | Total Paid: 0.000004152853926498 tRBTC (934202 gas * avg 0.004445349 gwei)
                                                                                

==========================

ONCHAIN EXECUTION COMPLETE & SUCCESSFUL.

Transactions saved to: /Users/rookiecol/Documents/code/rootstock/starter-kits/rootstock-foundry-starterkit/broadcast/Deploy.s.sol/31/run-latest.json

Sensitive values saved to: /Users/rookiecol/Documents/code/rootstock/starter-kits/rootstock-foundry-starterkit/cache/Deploy.s.sol/31/run-latest.json

Interacting with the Contract - Minting a Token

If the contract is already deployed, then you can interact with it using cast this command allows you to interact with the contract, in this case, read the balance of an account.

Reading the Balance of an Account

In your terminal, run the following command, replacing the placeholders with actual values:

cast call <contract_address> "balanceOf(address)(uint256)" <wallet_address> --rpc-url <rpc_url>

The result should look like this:

1000000000000000000000 [1e21]

Final Comments

You can explore the folders and files within the starter kit and customize the kit to suit your project’s needs. You can also learn how to import .env variables for deploying smart contracts, test smart contracts with solidity, etc.