Using Hardhat

What is Hardhat

Hardhat is a development environment to compile, deploy, test, and debug your smart contract.

Setting up the development environment

There are a few technical requirements before we start. Please install the following: Requirements:

Installing

There are a few technical requirements before we start. Please install the following: Requirements:

First, you need to create an empty project npm init --yes

Once your project is ready, you should run

npm install --save-dev hardhat
It's recommeded to install some dependencies.

npm install --save-dev @nomiclabs/hardhat-waffle ethereum-waffle chai @nomiclabs/hardhat-ethers ethers
To use your local installation of Hardhat, you need to use npx to run it (i.e. npx hardhat).

Create A Project

To create your Hardhat project run npx hardhat in your project folder:

mkdir MegaCoin
cd MegaCoin
  • Intialize your project:
$ npx hardhat
888    888                      888 888               888
888    888                      888 888               888
888    888                      888 888               888
8888888888  8888b.  888d888 .d88888 88888b.   8888b.  888888
888    888     "88b 888P"  d88" 888 888 "88b     "88b 888
888    888 .d888888 888    888  888 888  888 .d888888 888
888    888 888  888 888    Y88b 888 888  888 888  888 Y88b.
888    888 "Y888888 888     "Y88888 888  888 "Y888888  "Y888

Welcome to Hardhat v2.0.8

? What do you want to do? …
❯ Create a sample project
  Create an empty hardhat.config.js
  Quit

Once this project is initialized, you'll now have a project structure with the following items:

  • contracts/: Directory for Solidity contracts
  • scripts/: Directory for scriptable deployment files
  • test/: Directory for test files for testing your application and contracts
  • hardhat-config.js: Hardhat configuration file

Create Contract

You can write your own smart contract or download the BEP20 token smart contract template.

Config Hardhat for BSC

  • Go to hardhat.config.js
  • Update the config with bsc-network-crendentials.
require("@nomiclabs/hardhat-waffle");
require('@nomiclabs/hardhat-ethers');
const { mnemonic } = require('./secrets.json');

// This is a sample Hardhat task. To learn how to create your own go to
// https://hardhat.org/guides/create-task.html
task("accounts", "Prints the list of accounts", async () => {
  const accounts = await ethers.getSigners();

  for (const account of accounts) {
    console.log(account.address);
  }
});

// You need to export an object to set up your config
// Go to https://hardhat.org/config/ to learn more

/**
 * @type import('hardhat/config').HardhatUserConfig
 */
module.exports = {
  defaultNetwork: "mainnet",
  networks: {
    localhost: {
      url: "http://127.0.0.1:8545"
    },
    hardhat: {
    },
    testnet: {
      url: "https://data-seed-prebsc-1-s1.binance.org:8545",
      chainId: 97,
      gasPrice: 20000000000,
      accounts: {mnemonic: mnemonic}
    },
    mainnet: {
      url: "https://bsc-dataseed.binance.org/",
      chainId: 56,
      gasPrice: 20000000000,
      accounts: {mnemonic: mnemonic}
    }
  },
  solidity: {
  version: "0.5.16",
  settings: {
    optimizer: {
      enabled: true
    }
   }
  },
  paths: {
    sources: "./contracts",
    tests: "./test",
    cache: "./cache",
    artifacts: "./artifacts"
  },
  mocha: {
    timeout: 20000
  }
};

Note

It requires mnemonic to be passed in for Provider, this is the seed phrase for the account you'd like to deploy from. Create a new .secret file in root directory and enter your 12 word mnemonic seed phrase to get started. To get the seedwords from metamask wallet you can go to Metamask Settings, then from the menu choose Security and Privacy where you will see a button that says reveal seed words.

Compile Contract

To compile a Hardhat project, change to the root of the directory where the project is located and then type the following into a terminal:

npx hardhat compile

Deploying on BSC Network

Run this command in root of the project directory:

$  npx hardhat run --network testnet scripts/deploy.js

Remember your address, transaction_hash and other details provided would differ, Above is just to provide an idea of structure.

Congratulations! You have successfully deployed BEP20 Smart Contract. Now you can interact with the Smart Contract.

You can check the deployment status here: https://bscscan.com/ or https://testnet.bscscan.com/

Verify with Hardhat

Hardhat has an Etherscan plugin: Hardhat Etherscan plugin

Note: Hardhat was previously Buidler.

Install the plugin

npm install --save-dev @nomiclabs/hardhat-etherscan

Configure the plugin in buidler.config.js

  • Add require("@nomiclabs/hardhat-etherscan");
  • Add Bscscan API key

Warning

keep secret and don’t commit to version control)

Go to register and get API key: https://bscscan.com/myapikey

  • Set compiler version to match what was deployed

Warning

Remove any unnecessary contracts and clear the artifacts otherwise these will also be part of the verified contract.

Run the following command:

npx buidler verify --network mainnet DEPLOYED_CONTRACT_ADDRESS "Constructor argument 1"
  • Example
$ npx hardhat  verify --network testnet 0xbF39886B4F91F5170934191b0d96Dd277147FBB2
Nothing to compile
Compiling 1 file with 0.5.16
Successfully submitted source code for contract
contracts/BEP20Token.sol:BEP20Token at 0xbF39886B4F91F5170934191b0d96Dd277147FBB2
for verification on Etherscan. Waiting for verification result...

Successfully verified contract BEP20Token on Etherscan.
https://testnet.bscscan.com/address/0xbF39886B4F91F5170934191b0d96Dd277147FBB2#code