Deploying a Smart Contract

This recipe explains how to create, compile, deploy, and verify a simple smart contract on the Nero modular chain Testnet using Hardhat.

Hardhat

Hardhat is a toolset that allows you to compile, deploy, test, and verify your smart contracts.

Setting Up Your Workspace

• Node.js(https://nodejs.org)

Starting a New Project

To initiate a new project, run the following command:

To install Hardhat in your project, run the following command:

• To create a Hardhat project by running npx hardhat in your project directory.
• Then, you will be presented with several options for project creation. Select the appropriate options.

Figure 1: npx hardhat

Create Smart Contract

You can create your own smart contract or use the Openzeppelin token smart contract template(https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol), and place it in the contracts directory of your project.

Modify Hardhat for NERO

The updates to the <hardhat-config-file> and ./ignition/module/<deploy-file> files should resemble the following example (specific content should be adjusted according to requirements).

You’ll need a variables(https://hardhat.org/hardhat-runner/docs/guides/configuration-variables#configuration-variables) with the following contents:

NERO_TESTNET_PROVIDER_URL=https://rpc-testnet.nerochain.io
PRIVATE_KEY=add your own private key
API_KEY=add your own etherscan api key

You’ll need a hardhat.config.js and hardhat.config.ts with the following contents:

  require("@nomicfoundation/hardhat-toolbox");
  require("@nomicfoundation/hardhat-ignition-ethers");
  const { vars } = require("hardhat/config");
 
  const NERO_TESTNET_PROVIDER_URL = vars.get("NERO_TESTNET_PROVIDER_URL");
  const PRIVATE_KEY = vars.get("PRIVATE_KEY");
 
  module.exports = {
  solidity: "0.8.24",
  defaultNetwork: "nero_testnet",
  networks: {
      nero_testnet: {
      url: NERO_TESTNET_PROVIDER_URL,
      accounts: [PRIVATE_KEY],
      },
  },
  etherscan: {
      apiKey: API_KEY,
      customChains: [
      {
          network: "nero_testnet",
          chainId: 689,
          urls: {
          apiURL: "https://api-testnet.neroscan.io/api",
          browserURL: "https://testnet.neroscan.io",
          },
      },
      ],
      enabled: true
      },
  };
 

import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";
import "@nomicfoundation/hardhat-ignition-ethers";
import { vars } from "hardhat/config";
 
const NERO_TESTNET_PROVIDER_URL = vars.get("NERO_TESTNET_PROVIDER_URL");
const PRIVATE_KEY = vars.get("PRIVATE_KEY");
const API_KEY = vars.get("API_KEY");//(optional)
 
const config: HardhatUserConfig = {
  solidity: "0.8.24",
  defaultNetwork: "nero_testnet",
  networks: {
    nero_testnet: {
      url: NERO_TESTNET_PROVIDER_URL,
      accounts: [PRIVATE_KEY],
    },
  },
  etherscan: {//(optional)
    apiKey: API_KEY,
    customChains: [
      {
        network: "nero_testnet",
        chainId: 689,
        urls: {
          apiURL: "https://api-testnet.neroscan.io/api",
          browserURL: "https://testnet.neroscan.io",
        },
      },
    ],
    enabled: true
  },
};
export default config;

NOTE: You can obtain test coins from this faucet(https://app.testnet.nerochain.io/faucet)

Deploy Smart Contract on Nero Network

1. Compile the contract by running npx hardhat compilein the terminal.
2. Run npx hardhat ignition deploy ./ignition/modules/<deploy-file> --network <select-network> in the root of the project directory.
3. Visit the Testnet Explorer(https://testnet.neroscan.io/) to view the deployed contract.

Congratulations! You have successfully deployed your own Smart Contract.

Figure 2: NERO testnet scan

Conclusion

This recipe has walked you through creating and deploying a basic smart contract using Hardhat. Although the recipe used the testnet, you can follow the same process for the mainnet.​​