Create HelloWorld Contract Using Hardhat

See the full GitHub Project Code Repository.

This developer guide will walk you through setting up a new Solidity contract, configuring the Berachain network details, deploying to Berachain, and verifying the contract, all with Hardhat.

Requirements

Before beginning, make sure you have the following installed or setup on your computer before hand.

• NVM or Node v22.14.0 or greater
• pnpm v10.15.0 or greater
• Wallet that contains BERA token (for deployment)

WARNING

Hardhat v3.0.0 or greater is needed to be installed for verification.

Creating HelloWorld Project Code Setup

Start by creating a new project folder for the project:

mkdir create-helloworld-contract-using-hardhat;
cd create-helloworld-contract-using-hardhat;

Initiate Hardhat to build out the viem template with the following prompts:

# FROM ./create-helloworld-contract-using-hardhat;

pnpm dlx hardhat --init;

# [Expected Prompts]:
#
#  █████  █████                         ███  ███                  ███      ██████
# ░░███  ░░███                         ░███ ░███                 ░███     ███░░███
#  ░███   ░███   ██████  ████████   ███████ ░███████    ██████  ███████  ░░░  ░███
#  ░██████████  ░░░░░███░░███░░███ ███░░███ ░███░░███  ░░░░░███░░░███░      ████░
#  ░███░░░░███   ███████ ░███ ░░░ ░███ ░███ ░███ ░███   ███████  ░███      ░░░░███
#  ░███   ░███  ███░░███ ░███     ░███ ░███ ░███ ░███  ███░░███  ░███ ███ ███ ░███
#  █████  █████░░███████ █████    ░░███████ ████ █████░░███████  ░░█████ ░░██████
# ░░░░░  ░░░░░  ░░░░░░░ ░░░░░      ░░░░░░░ ░░░░ ░░░░░  ░░░░░░░    ░░░░░   ░░░░░░
#
# 👷 Welcome to Hardhat v3.0.6 👷
#
# ✔ Which version of Hardhat would you like to use? · hardhat-3
# ✔ Where would you like to initialize the project? · /path/to/create-helloworld-contract-using-hardhat
# Please provide either a relative or an absolute path: · .
# ✔ What type of project would you like to initialize? · node-test-runner-viem
# ✨ Template files copied ✨
# ✔ You need to install the necessary dependencies using the following command:
# pnpm add --save-dev "hardhat@^3.0.6" "@nomicfoundation/hardhat-toolbox-viem@^5.0.0" "@nomicfoundation/hardhat-ignition@^3.0.0" "@types/node@^22.8.5" "forge-std@foundry-rs/forge-std#v1.9.4" "typescript@~5.8.0" "viem@^2.30.0"
#
# Do you want to run it now? (Y/n) · true

Creating the HelloWorld Contract

Now that we have everything, there should be some existing files that were created by Hardhat.

We'll start by creating a new Solidity contract by renaming the existing to the following:

# FROM ./create-helloworld-contract-using-hardhat;

# Renames `Counter.sol` to `HelloWorld.sol`
mv contracts/Counter.sol contracts/HelloWorld.sol;

In our new HelloWorld.sol file, we'll replace the existing code with the following:

File: ./contract/HelloWorld.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.28;

contract HelloWorld {
    // Events that allows for emitting a message
    event NewGreeting(address sender, string message);

    // Variables
    string greeting;

    // Main constructor run at deployment
    constructor(string memory _greeting) {
        greeting = _greeting;
        emit NewGreeting(msg.sender, _greeting);
    }

    // Get function
    function getGreeting() public view returns (string memory) {
        return greeting;
    }

    // Set function
    function setGreeting(string memory _greeting) public {
        greeting = _greeting;
        emit NewGreeting(msg.sender, _greeting);
    }
}

We'll also modify the default Counter.t.sol file that's used for foundry tests.

# FROM ./create-helloworld-contract-using-hardhat;

# Renames `Counter..t.sol` to `HelloWorld.t.sol`
mv contracts/Counter.t.sol contracts/HelloWorld.t.sol;

We'll also modify the file with the following contents:

File: ./contracts/HelloWorld.t.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.28;

import {HelloWorld} from "./HelloWorld.sol";
import {Test} from "forge-std/Test.sol";

contract HelloWorldTest is Test {
  HelloWorld helloWorld;

  function setUp() public {
    helloWorld = new HelloWorld("Hello World");
  }

  function test_InitialValue() public view {
    require(helloWorld.getGreeting() == "Hello World", "Initial value should be 'Hello World'");
  }

  function test_SetGreet() public {
    helloWorld.setGreeting("Hello There");
    require(helloWorld.getGreeting() == "Hello There", "Value should be 'Hello There'");
  }
}

Now that we have our Solidity contract, let's make sure it can compile correctly.

# FROM ./create-helloworld-contract-using-hardhat;

./node_modules/.bin/hardhat compile;

# [Expected Output]:
# Compiling your Solidity contracts...
# Compiled 1 Solidity file with solc 0.8.28 (evm target: cancun)

Let's make this step a bit easier by adding this command to our package.json

File: ./package.json

{
  "name": "create-helloworld-contract-using-hardhat",
  "scripts": {
    "compile": "./node_modules/.bin/hardhat compile"
  }, 
  "devDependencies": {
    "@nomicfoundation/hardhat-ignition": "^3.0.3",
    "@nomicfoundation/hardhat-toolbox-viem": "^5.0.0",
    "@types/node": "^22.18.1",
    "forge-std": "github:foundry-rs/forge-std#v1.9.4",
    "hardhat": "^3.0.6",
    "typescript": "~5.8.3",
    "viem": "^2.37.5"
  }
}

We can take advantage of compiling with the following command:

# FROM ./create-helloworld-contract-using-hardhat;

pnpm compile; # npm run compile or yarn run compil;

# [Expected Output]:
# Nothing to compile

Testing the HelloWorld Contract

Now that we have our contract, let's make sure it's working correctly by writting some tests.

Hardhat already created a test file in our /test directory, and we're going to rename it.

# FROM ./create-helloworld-contract-using-hardhat;

# Renames `Counter.ts` to `HelloWorld.test.ts`
mv test/Counter.ts test/HellWorld.test.ts;

In our new HelloWorld.test.ts file, we'll replace the existing code with the following:

File: ./test/HelloWorld.test.ts

// Imports
// ========================================================
import assert from "node:assert/strict";
import { describe, it } from "node:test";
import { network } from "hardhat";

// Tests
// ========================================================
describe("HelloWorld", async () => {
  const { viem } = await network.connect();

  /**
   * Deployment tests
   */
  describe("Deployment", async () => {
    /**
     * Contract setup
     */
    const contract = await viem.deployContract("HelloWorld", ["Hello World"]);

    /**
     * Test initial deployment
     */
    it("Should deploy with original message", async () => {
      // Init + Expectations
      assert.equal(await contract.read.getGreeting(), "Hello World");
    });

    /**
     * Test modifying the message
     */
    it("Should set a new message", async function () {
      // Init
      await contract.write.setGreeting(["Hello There"]);

      // Expectations
      assert.equal(await contract.read.getGreeting(), "Hello There");
    });
  });
});

With our new tests defined, let's run our tests with the following command:

# FROM ./create-helloworld-contract-using-hardhat;

./node_modules/.bin/hardhat test;

# [Expected Output]:
# Compiling your Solidity contracts...
#
# Nothing to compile
#
# Running Solidity tests
#
#   0 passing
#
# Running node:test tests
#
#   HelloWorld
#     Deployment
#       ✔ Should deploy with original message
#       ✔ Should set a new message
#   2 passing (860ms)

Let's make this step a bit easier again by adding this command to our package.json so that we can easily run pnpm test,

File: ./package.json

{
  "name": "create-helloworld-contract-using-hardhat",
  "scripts": {
    "compile": "./node_modules/.bin/hardhat compile",
    "test": "./node_modules/.bin/hardhat test", 
    "keystore:set": "./node_modules/.bin/hardhat keystore set --"
  },
  "devDependencies": {
    "@nomicfoundation/hardhat-ignition": "^3.0.3",
    "@nomicfoundation/hardhat-toolbox-viem": "^5.0.0",
    "@types/node": "^22.18.1",
    "forge-std": "github:foundry-rs/forge-std#v1.9.4",
    "hardhat": "^3.0.6",
    "typescript": "~5.8.3",
    "viem": "^2.37.5"
  }
}

Configuring Hardhat for Berachain Contract Deployment

In order to get our hardhat.config.ts setup correctly, let's take advantage of key store built into hardhat.

Set the RPC.

# FROM ./create-helloworld-contract-using-hardhat;

pnpm keystore:set BERACHAIN_RPC_URL;

# 👷🔐 Hardhat Production Keystore 🔐👷
#
# This is the first time you are using the production keystore, please set a password.
# The password must have at least 8 characters.
#
# [hardhat-keystore] Enter the password: **********
# [hardhat-keystore] Please confirm your password: **********
# [hardhat-keystore] Enter secret to store in the production keystore: **********************************
# Key "BERACHAIN_RPC_URL" set in the production keystore

Set your wallet private key.

# FROM ./create-helloworld-contract-using-hardhat;

pnpm keystore:set WALLET_PRIVATE_KEY;

# [hardhat-keystore] Enter the password: **********
# [hardhat-keystore] Enter secret to store in the production keystore: ****************************************************************
# Key "WALLET_PRIVATE_KEY" set in the production keystore

INFO

NOTE: If ever you need to overwrite a new value for your keystore, use ./node_modules/.bin/hardhat keystore set YOUR_KEY --force

With our environment variables setup, we can now load them into our hardhat.config.ts with the following code:

File: ./hardhat.config.ts

// Imports
// ========================================================
import type { HardhatUserConfig } from "hardhat/config";
import hardhatToolboxViemPlugin from "@nomicfoundation/hardhat-toolbox-viem";
import { configVariable } from "hardhat/config";

// Main Hardhat Config
// ========================================================
const config: HardhatUserConfig = {
  plugins: [hardhatToolboxViemPlugin],
  solidity: {
    profiles: {
      default: {
        version: "0.8.28"
      },
      production: {
        version: "0.8.28",
        settings: {
          optimizer: {
            enabled: true,
            runs: 200
          }
        }
      }
    }
  },
  networks: {
    berachainTestnet: {
      type: "http",
      chainType: "l1",
      url: configVariable("BERACHAIN_RPC_URL"),
      accounts: [configVariable("WALLET_PRIVATE_KEY")]
    },
    hardhatMainnet: {
      type: "edr-simulated",
      chainType: "l1"
    },
    hardhatOp: {
      type: "edr-simulated",
      chainType: "op"
    },
    sepolia: {
      type: "http",
      chainType: "l1",
      url: configVariable("SEPOLIA_RPC_URL"),
      accounts: [configVariable("WALLET_PRIVATE_KEY")]
    }
  }
};

// Exports
// ========================================================
export default config;

Deploying HelloWorld Contract

Now that we have the configuration setup, let's try running a local node and deploying it there.

But first, let's make it a bit easier by making some modifications to our package.json to make these commands a bit easier to run.

File: ./package.json

{
  "name": "create-helloworld-contract-using-hardhat",
  "scripts": {
    "compile": "./node_modules/.bin/hardhat compile",
    "test": "./node_modules/.bin/hardhat test",
    "keystore:set": "./node_modules/.bin/hardhat keystore set --",
    "node": "./node_modules/.bin/hardhat node", 
    "deploy:localhost": "./node_modules/.bin/hardhat ignition deploy --network localhost ignition/modules/HelloWorld.ts", 
    "deploy:berachain": "./node_modules/.bin/hardhat ignition deploy --network berachainTestnet ignition/modules/HelloWorld.ts"
  },
  "devDependencies": {
    "@nomicfoundation/hardhat-toolbox-viem": "^1.0.0",
    "hardhat": "^2.18.3"
  }
}

Let's modify the existing ignition module.

# FROM: /

mv ignition/modules/Counter.ts ignition/modules/HelloWorld.ts;

We'll also need to configure our ./ignition/modules/HelloWorld.ts script to make sure things are deployed correctly.

File: ./ignition/modules/HelloWorld.ts

// Imports
// ========================================================
import { buildModule } from "@nomicfoundation/hardhat-ignition/modules";

// Main Module
// ========================================================
export default buildModule("HelloWorldModule", (m) => {
  const helloWorld = m.contract("HelloWorld", ["Hello World"]);

  m.call(helloWorld, "setGreet", ["Hello There"]);

  return { helloWorld };
});

With our deployment script set, let's run a local node in one Terminal and deploy the contract in another Terminal.

Terminal 1

# FROM ./create-helloworld-contract-using-hardhat;

pnpm node;

# [Expected Output]:
# Started HTTP and WebSocket JSON-RPC server at http://127.0.0.1:8545/
#
# Accounts
# ========
#
# WARNING: These accounts, and their private keys, are publicly known.
# Any funds sent to them on Mainnet or any other live network WILL BE LOST.
#
# Account #0: 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266 (10000 ETH)
# Private Key: 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80

Teminal 2

# FROM ./create-helloworld-contract-using-hardhat;

pnpm deploy:localhost;
# [Expected Similar Output]:
# Hardhat Ignition starting for [ HelloWorldModule
# Hardhat Ignition 🚀
#
# Deploying [ HelloWorldModule ]
#
# Batch #1
#   Executed HelloWorldModule#HelloWorld
#
# Batch #2
# Batch #2
# Batch #2
#   Executed HelloWorldModule#HelloWorld.setGreet
#
# [ HelloWorldModule ] successfully deployed 🚀
#
# Deployed Addresses
#
# HelloWorldModule#HelloWorld - 0x5FbDB2315678afecb367f032d93F642f64180aa3

Now that we can see that the contract can be successfully deployed for a local node, let's deploy directly to Berachain.

# FROM ./create-helloworld-contract-using-hardhat;

pnpm deploy:berachain;

# [Expected Similar Output]:
# [hardhat-keystore] Enter the password: **********
# ✔ Confirm deploy to network berachainTestnet (80069)? … yes
# Hardhat Ignition 🚀
#
# Deploying [ HelloWorldModule ]
#
# Batch #1
#   Executed HelloWorldModule#HelloWorld
#
# Batch #2
#   Executed HelloWorldModule#HelloWorld.setGreet
#
# [ HelloWorldModule ] successfully deployed 🚀
#
# Deployed Addresses
#
# HelloWorldModule#HelloWorld - 0x2ACD9577B57Ff043F0203730683e8c7C881DcB21

We can also see our deployed contract in the Berachain Block Explorer by going to the following address:

open https://testnet.berascan.com/address/0x2ACD9577B57Ff043F0203730683e8c7C881DcB21

# [Expected Result Should Open Your Browser]

You'll see that our contract has been successfully deployed but not verified as it still shows the contract bytecode.

Verifying HelloWorld Contract

Next, we'll be using Etherscan to verify our contract and for this we'll need to add an Etherscan API Key.

INFO

Etherscan API V2 now let's you use any Etherscan API key across multiple platforms at https://etherscan.io/login.

Add the key by running:

# FROM ./create-helloworld-contract-using-hardhat;

pnpm keystore:set ETHERSCAN_API_KEY;

# [Expected Similar Output]:
# [hardhat-keystore] Enter the password: **********
# [hardhat-keystore] Enter secret to store in the production keystore: *********************************
# Key "ETHERSCAN_API_KEY" set in the production keystore

Next, we'll need to modify our configuration file to allow for Bepolia testnet.

File: ./hardhat.config.ts

// Imports
// ========================================================
import type { HardhatUserConfig } from "hardhat/config";
import hardhatToolboxViemPlugin from "@nomicfoundation/hardhat-toolbox-viem";
import { configVariable } from "hardhat/config";

// Main Hardhat Config
// ========================================================
const config: HardhatUserConfig = {
  plugins: [hardhatToolboxViemPlugin],
  solidity: {
    profiles: {
      default: {
        version: "0.8.28",
      },
      production: {
        version: "0.8.28",
        settings: {
          optimizer: {
            enabled: true,
            runs: 200,
          },
        },
      },
    },
  },
  networks: {
    berachainTestnet: {
      type: "http",
      chainType: "l1",
      url: configVariable("BERACHAIN_RPC_URL"),
      accounts: [configVariable("WALLET_PRIVATE_KEY")],
    },
    hardhatMainnet: {
      type: "edr-simulated",
      chainType: "l1",
    },
    hardhatOp: {
      type: "edr-simulated",
      chainType: "op",
    },
    sepolia: {
      type: "http",
      chainType: "l1",
      url: configVariable("SEPOLIA_RPC_URL"),
      accounts: [configVariable("WALLET_PRIVATE_KEY")],
    },
  },
  verify: { 
    etherscan: { 
      apiKey: configVariable("ETHERSCAN_API_KEY"), 
    }, 
  }, 
  chainDescriptors: { 
    80069: { 
      name: "Berachain Bepolia", 
      blockExplorers: { 
        etherscan: { 
          name: "BeraScan Block Explorer", 
          url: "https://testnet.berascan.com/", 
          apiUrl: "https://api.etherscan.io/v2/api", 
        } 
      } 
    }, 
  } 
};

// Exports
// ========================================================
export default config;

Now that we have the configuration setup, let's add another run command to our package.json

File: ./package.json

{
  "name": "create-helloworld-contract-using-hardhat",
  "scripts": {
    "compile": "./node_modules/.bin/hardhat compile",
    "test": "./node_modules/.bin/hardhat test",
    "keystore:set": "./node_modules/.bin/hardhat keystore set --",
    "node": "./node_modules/.bin/hardhat node",
    "deploy:localhost": "./node_modules/.bin/hardhat ignition deploy --network localhost ignition/modules/HelloWorld.ts",
    "deploy:berachain": "./node_modules/.bin/hardhat ignition deploy --network berachainTestnet ignition/modules/HelloWorld.ts",
    "verify:berachain": "./node_modules/.bin/hardhat verify --network berachainTestnet --"
  },
  "devDependencies": {
    "@nomicfoundation/hardhat-toolbox-viem": "^1.0.0",
    "hardhat": "^2.18.3"
  }
}

With our previously deploy contract address and taking into account that we deployed our contract with the initial argument of "Hello World", let's run the following to confirm our contract.

# FROM ./create-helloworld-contract-using-hardhat;

# Equivalent to: npx hardhat verify 0x2ACD9577B57Ff043F0203730683e8c7C881DcB21 "Hello World"
pnpm verify:berachain 0x2ACD9577B57Ff043F0203730683e8c7C881DcB21 "Hello World";

# [Expected Output]:
# === Etherscan ===
# [hardhat-keystore] Enter the password: **********
#
# 📤 Submitted source code for verification on Berascan:
#
#   contracts/HelloWorld.sol:HelloWorld
#   Address: 0x2ACD9577B57Ff043F0203730683e8c7C881DcB21
#
# ⏳ Waiting for verification result...
#
# ✅ Contract verified successfully on Berascan!
#
#   contracts/HelloWorld.sol:HelloWorld
#   Explorer: https://testnet.berascan.com/address/0x2ACD9577B57Ff043F0203730683e8c7C881DcB21#code
#
# === Blockscout ===
# HHE80027: No Blockscout block explorer is configured for the 80069 chain in the chain descriptors.
#  ELIFECYCLE  Command failed with exit code 1.

We should now see with the block explorer that the contract is verified and that the Solidity code is now showing.

Full Code Repository

The full github code repository can be found in the guides section of this repository under Create HelloWorld Contract Using Hardhat.