Migrating project from Hardhat Local Blockchain to Live Testnet Blockchain | by Takshil Patil | Coinmonks | Aug, 2022 - Rvpg media

Migrating project from Hardhat Local Blockchain to Live Testnet Blockchain | by Takshil Patil | Coinmonks | Aug, 2022

Why I wrote this blog? When I started development using hardhat, I only used the local environment for testing, but when I tried to deploy and test my web3 app on a live testnet, I faced a lot of problems and had confusions. The below are article addresses these problems. Also I have found differences in data that a transaction has while in local solidity development vs live blockchain.

Unwanted errors

Below is one of the errors I was getting while migrating to testnet blockchain.

This error was cause because I have not cleaned up hardhat artifacts before deploying the smart contract to onchain testnet or mainnet using npx hardhat clean.

Difference in transaction logs output in local environment vs onchain testnet or mainnet

Below is a difference between a event log of hardhat local transaction vs live onchain blockchain event log.

#pending, details will be added soon.

1. Hardhat Runtime Global variable

Ref: https://hardhat.org/hardhat-runner/docs/advanced/hardhat-runtime-environment#as-global-variables

  • This happens when we dont specify any config about the blockchain. But practically, we want to control where our smart contract is deployed, rather than some global variable who only runs “Hardhat Runtime Only Blockchain”.
  • Before running a task, test or script, Hardhat injects the HRE into the global scope, turning all of its fields into global variables.
  • When the task execution is completed, these global variables are removed, restoring their original value, if they had one.

2. const { ethers } = require(“hardhat”);

This is the recommended approach by me.

  • This is a version ether.js library + few hardhat helpers to ease smart contract development in hardhat.

3. import { ethers } from ‘ethers’;

  • This is the ether.js library without any hardhat helpers.

4. import { EtherscanProvider } from ‘@ethersproject/providers’;

  • This library is used to fetch providers.

Github Repo: https://github.com/Le4kno3/Solidity-Contracts/tree/main/nftmarketplace-contract-3

Important Note: Whenever you are moving from hardhat runtime or hardhat local node to a onchain testnet or mainnnet, make sure to run npx hardhat clean to remove all the earlier files, else you will get unwanted errors. Also make sure the onchain wallets have required tokens or coins to perform the deployment and stransactions.

  • This is my preferred approach, rather than using the hardhat runtime environment.
  • I like to use the “hardhat node” local blockchain and do my complete development using it.
  • To create this local blockchain simply run the below command on another terminal.
npx hardhat node

Below is a sample deploy.ts

import * as fs from 'fs';
import { ethers } from "hardhat";
import * as dotenv from "dotenv";
dotenv.config();async function main() {const [owner, nftbuyer, nftseller] = await ethers.getSigners();
// Promise<ethers.Signer[]>
// We get the contract to deploy
const NFTMarket = await ethers.getContractFactory("NFTMarket", owner);
const myNFTMarket = await NFTMarket.deploy();
await myNFTMarket.deployed();
const signerAddress = await owner.getAddress();
const nftBuyerAddress = await nftbuyer.getAddress();
const nftSellerAddress = await nftseller.getAddress();
console.log("Owner address:", signerAddress);
console.log("NFT buyer address:", nftBuyerAddress);
console.log("NFT seller address:", nftSellerAddress);
console.log("NFTMarket contract deployed to:", myNFTMarket.address);
// We get the contract to deploy
const NFTToken = await ethers.getContractFactory("NFTToken", owner);
const myNFTToken = await NFTToken.deploy(myNFTMarket.address);
await myNFTToken.deployed();console.log("NFTToken contract deployed to:", myNFTToken.address);let config = `
export const nftMarketplaceAddress = "${myNFTMarket.address}"
export const nftTokenAddress = "${myNFTToken.address}"
export const nftContractOwner = "${signerAddress}"
export const nftBuyer = "${nftBuyerAddress}"
export const nftSeller = "${nftSellerAddress}"`;
let data = JSON.stringify(config);
fs.writeFileSync('cache/deploy.ts', JSON.parse(data));
// We recommend this pattern to be able to use async/await everywhere
// and properly handle errors.
.then(() => process.exit(0))
.catch((error) => {

After deployment the address of the contracts and the users addresses required during testing is stored in cache/deploy.ts. Once this is done you can use the below test script

import { ethers } from "hardhat";import { expect } from "chai";import { nftTokenAddress, nftMarketplaceAddress } from './../cache/deploy';
import NFTMarket from "../artifacts/contracts/NFTMarket.sol/NFTMarket.json";
import NFTToken from "../artifacts/contracts/NFTToken.sol/NFTToken.json";
let myNFTMarket: any;
let NFTMarketAddress: string;
let myNFTToken: any;
let NFTTokenAddress: string;
let ownerAddress: any;
let sellerAddress: any;
let buyerAddress: any;
let listingPrice: number;
let provider: any;
console.log("NFT Marketplace Address is: ", nftMarketplaceAddress);
console.log("NFT Token Address is: ", nftTokenAddress);
beforeEach(async () => {// provider = ethers.provider;
[ownerAddress, sellerAddress, buyerAddress] = await ethers.getSigners();
//set providermyNFTMarket = new ethers.Contract(nftMarketplaceAddress, NFTMarket.abi, ownerAddress);NFTMarketAddress = myNFTMarket.address;myNFTToken = new ethers.Contract(nftTokenAddress, NFTToken.abi, ownerAddress);NFTTokenAddress = myNFTToken.address;listingPrice = await myNFTMarket.connect(ownerAddress).getListingPrice();
// listingPrice = 0.0025;
describe("MarketPlace", () => {
it("Should deploy marketplace and NFT contracts", async () => {
const nftMarketAddress = await myNFTMarket.address;
it("Should have a listing price", async () => {const expectedListingPrice = ethers.utils.parseEther('0.0025');expect(listingPrice).to.equal(expectedListingPrice);});it("Should create market item", async () => {
//we are now creating 2 NFT tokens in the NFTToken contract
const tx = await myNFTToken.connect(ownerAddress).createToken("https://www.mytoken1.com");
// const tx2 = await myNFTToken.connect(ownerAddress).createToken("https://www.mytoken2.com");
// const count = await myNFTToken.tokenCount();
const itemPrice = ethers.utils.parseUnits('0.1', 'ether');//transaction of token
const tokenID = (await myNFTToken.getLastTokenID()).toString();
console.log("The created token ID is: ", tokenID);
let items = await myNFTMarket.fetchRemainingMarketItems();items = await Promise.all(items.map(async (i: { tokenId: { toString: () => any; }; price: { toString: () => any; }; seller: any; owner: any; }) => {
const tokenUri = await myNFTToken.tokenURI(i.tokenId);
let item = {
price: i.price.toString(),
tokenId: i.tokenId.toString(),
seller: i.seller,
owner: i.owner,
return item;

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