Verify a Smart Contract using the Hardhat Verification Plugin

Smart contracts are the backbone of decentralized applications (dApps). They automate agreements and processes, but their code can be complex and prone to errors. Verifying your smart contracts is crucial to ensure they function as intended.

This tutorial will guide you through verifying your contracts using the Hardhat Verification Plugin on the Rootstock Explorer and Blockscout Explorer with a single command. This plugin simplifies the verification of Solidity smart contracts deployed on the Rootstock network. By verifying the contracts, you allow block explorers like Rootstock and Blockscout to link your contract's source code with its deployed bytecode on the blockchain, allowing for more trustless interaction with the code.

In this tutorial, we'll do the following steps:

• Set up your hardhat config environment in your project
• Use the hardhat-verify plugin to verify a contract address.

Prerequisites

To follow this tutorial, you should have knowledge of the following:

• Hardhat
• Basic knowledge of smart contracts

Hardhat Starter dApp

A Hardhat Starter dApp has been created with preset configuration for the Rootstock network. Clone and follow the instructions in the README to setup the project. Note: To set the .env variables to match the hardhat.config.ts file, if using the starter dApp for this tutorial.

What is hardhat-verify?

Hardhat is a full-featured development environment for contract compilation, deployment and verification. The hardhat-verify plugin supports contract verification on the Rootstock Explorer and Rootstock Blockscout Explorer.

Installation

npm install --save-dev @nomicfoundation/hardhat-verify

And add the following code to your hardhat.config.ts file:

require("@nomicfoundation/hardhat-verify");

Or, if you are using TypeScript, add this to your hardhat.config.ts:

import "@nomicfoundation/hardhat-verify";

Usage

You need to add the following Etherscan config to your hardhat.config.ts file:

require('@nomicfoundation/hardhat-toolbox');
require('@nomicfoundation/hardhat-verify');
require('dotenv').config();

module.exports = {
  defaultNetwork: 'rootstockTestnet',
  networks: {
    rootstockMainnet: {
      url: 'https://public-node.rsk.co',
      chainId: 30,
      accounts: [PRIVATE_KEY],
    },
    rootstockTestnet: {
      url: 'https://public-node.testnet.rsk.co',
      chainId: 31,
      accounts: [PRIVATE_KEY],
    },
  },
  solidity: {
    compilers: [
      {
        version: '0.8.25',
      },
    ],
  },
  sourcify: {
    enabled: false,
  },
  etherscan: {
    apiKey: {
      // Is not required by Blockscout or Rootstock explorers, 
      // but must be any non-empty string, si leave it as "rootstock".
      rootstockTestnet: 'rootstock',
      rootstockMainnet: 'rootstock',
    },
    customChains: [
      {
        network: 'rootstockTestnet',
        chainId: 31,
        urls: {
          apiURL: 'https://be.explorer.testnet.rootstock.io/api/v3/',
          browserURL: 'https://explorer.testnet.rootstock.io/',
        },
      },
      {
        network: 'rootstockMainnet',
        chainId: 30,
        urls: {
          apiURL: 'https://be.explorer.rootstock.io/api/v3/',
          browserURL: 'https://explorer.rootstock.io/',
        },
      },
    ],
  },
  blockscout: {
    enabled: true,
    customChains: [
      {
        network: 'rootstockTestnet',
        chainId: 31,
        urls: {
          apiURL: 'https://rootstock-testnet.blockscout.com/api/',
          browserURL: 'https://rootstock-testnet.blockscout.com/',
        },
      },
      {
        network: 'rootstockMainnet',
        chainId: 30,
        urls: {
          apiURL: 'https://rootstock.blockscout.com/api/',
          browserURL: 'https://rootstock.blockscout.com/',
        },
      },
    ],
  },
};

Now, run the verify task, passing the address of the contract, the network where it's deployed, and the constructor arguments that were used to deploy the contract:

npx hardhat verify --network rootstockTestnet DEPLOYED_CONTRACT_ADDRESS CONSTRUCTOR_ARGUMENTS

or

npx hardhat verify --network rootstockMainnet DEPLOYED_CONTRACT_ADDRESS CONSTRUCTOR_ARGUMENTS

Tip

• Replace DEPLOYED_CONTRACT_ADDRESS with the contract address that you want to verify.

The response should look like this:

npx hardhat verify --network rootstockTestnet 0x1b4951c57ce2c53addcfa173d1106b5e12f11e38 1000 MyToken23 MTK23
Successfully submitted source code for contract
contracts/MyToken.sol:MyToken at 0x1b4951c57ce2c53addcfa173d1106b5e12f11e38
for verification on the block explorer. Waiting for verification result...

Successfully verified contract MyToken on the block explorer.
https://explorer.testnet.rootstock.io/address/0x1b4951c57ce2c53addcfa173d1106b5e12f11e38#code

Successfully verified contract MyToken on the block explorer.
https://rootstock-testnet.blockscout.com/address/0x1b4951c57ce2c53addcfa173d1106b5e12f11e38#code

With that, the contract has been successfully verified in both block explorers.

Resources

• Deploy, Interact and Verify Smart Contracts using Remix and Rootstock Explorer
• Visit hardhat-verify
• Visit blockscout
• Hardhat Starter Kit for Rootstock