This workshop is targeted at developers who are transitioning from Web2 to Web3 or have just recently gotten into Web3 and are looking to have a well-rounded foundation.
This first workshop is Series 1 in the three-part series that aims to introduce you to the blockchain and how to build on the blockchain.
Let's ensure we have Node/NPM installed on our PC. If we don't have it installed, head over here for a guide.
Let's run the following command:
npm init -y
npm install --save-dev hardhat
Next, let's get a sample project by running the command below:
npx hardhat
We'll go with the following options:
- A JavaScript project.
- Accept all other requests.
Installing hardhat-waffle and hardhat-ethers is required for the sample project.
Just in case it didn't install automatically, we will install this other requirement with the following command:
npm install --save-dev @nomiclabs/hardhat-waffle ethereum-waffle chai @nomiclabs/hardhat-ethers ethers @openzeppelin/contracts
To make sure everything is working, let us run the command below.
npx hardhat test
We will see a passed test result in our console.
It is now okay for us to delete Lock.js from the test folder and delete deploy.js from the scripts directory.
After that, go to contracts folder and delete Lock.sol.
The folders themselves should not be deleted!
We'll create a CoffeePortal.sol file inside the contracts directory. When using Hardhat, file layout is crucial, so pay attention!
We're going to start with the basic structure of every contract.
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.9;
// Import this file to use console.log
import "hardhat/console.sol";
contract CoffeePortal {
constructor() {
console.log("CoffeePortal deployed!");
}
}
To test our smart contract, we will navigate to the test folder, create a new coffee-test.js file, and update it with the following code snippet:
const { expect } = require("chai");
describe("CoffeePortal", function () {
it("Should be able to deploy a contract", async function () {
const CoffeePortal = await ethers.getContractFactory("CoffeePortal");
const coffeePortal = await CoffeePortal.deploy();
expect(coffeePortal.address).to.be.a("string");
});
});
We have successfully build and test the demo(starter) smart contract in the previous step, Let us deploy it to a local network.
Inside the scripts folder, we will create a deploy.js file. Add the following code snippet.
// We require the Hardhat Runtime Environment explicitly here. This is optional
// but useful for running the script in a standalone fashion through `node <script>`.
//
// You can also run a script with `npx hardhat run <script>`. If you do that, Hardhat
// will compile your contracts, add the Hardhat Runtime Environment's members to the
// global scope, and execute the script.
const main = async () => {
const [deployer] = await hre.ethers.getSigners();
const accountBalance = await deployer.getBalance();
console.log("Deploying contracts with account: ", deployer.address);
console.log("Account balance: ", accountBalance.toString());
// Deploy the contract
const coffeeContractFactory = await hre.ethers.getContractFactory("CoffeePortal");
const coffeeContract = await coffeeContractFactory.deploy();
await coffeeContract.deployed(); // Await contract to be deployed
console.log("Portal address: ", coffeeContract.address);
};
const runMain = async () => {
try {
await main();
process.exit(0);
} catch (error) {
console.error(error);
process.exit(1);
}
};
runMain();
Before deploying, let us ensure we have our local node up and running in a separate terminal with the following command.
npx hardhat node
Next, we will deploy our smart contract.
npx hardhat run scripts/deploy.js --network localhost
Building the CoffeePortal(BuyMeACoffee) smart contract,
Lt us update the CoffeePortal.sol with the following code snippet.
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.9;
// Import this file to use console.log
import "hardhat/console.sol";
contract CoffeePortal {
uint256 totalCoffee;
address payable public owner;
/*
* A little magic, Events in Solidity!
*/
event NewCoffee(
address indexed from,
uint256 timestamp,
string message,
string name
);
constructor() payable {
console.log("Smart Contract Deployed!");
// user who is calling this function address
owner = payable(msg.sender);
}
/*
* Create a struct here named Coffee.
* A struct is basically a custom datatype where we can customize what we want to hold inside it.
*/
struct Coffee {
address giver; // The address of the user who buys me a coffee.
string message; // The message the user sent.
string name; // The name of the user who buys me a coffee.
uint256 timestamp; // The timestamp when the user buys me a coffee.
}
/*
* Declare variable coffee that lets me store an array of structs.
* This is what hold all the coffee anyone has ever sends to me!
*/
Coffee[] coffee;
/*
* Added a function getAllCoffee which will return the struct array, coffee, to us.
* This will make it easy to retrieve the coffee from our website!
*/
function getAllCoffee() public view returns (Coffee[] memory) {
return coffee;
}
// Get All coffee bought
function getTotalCoffee() public view returns (uint256) {
// Optional: Add this line if you want to see the contract print the value!
// We'll also print it over in run.js as well.
console.log("We have %d total coffee recieved ", totalCoffee);
return totalCoffee;
}
/*
* Function to buy a coffee
*/
function buyCoffee(string memory _message, string memory _name) public payable {
// Must accept more than 0 ETH for a coffee.
require(msg.value > 0, "can't buy coffee for free!");
// Add one coffe to he total coffee bought
totalCoffee += 1;
console.log("%s has just sent a coffee!", msg.sender);
/*
* Store the coffee data in the array.
*/
coffee.push(Coffee(msg.sender, _message, _name, block.timestamp));
// Send the coffee Eth to the owner of the contract.
owner.transfer(address(this).balance);
emit NewCoffee(msg.sender, block.timestamp, _message, _name);
}
}
Writing test for our smart contract. Add the following code snippet.
const { expect } = require("chai");
describe("CoffeePortal", function () {
it("Should be able to deploy a contract", async function () {
const CoffeePortal = await ethers.getContractFactory("CoffeePortal");
const coffeePortal = await CoffeePortal.deploy();
expect(coffeePortal.address).to.be.a("string");
});
it("Should be able to buy a coffee", async function () {
const CoffeePortal = await ethers.getContractFactory("CoffeePortal");
const coffeePortal = await CoffeePortal.deploy();
const [giver1] = await ethers.getSigners();
const coffeeTxn1 = await coffeePortal.connect(giver1).buyCoffee(
"This is the coffee #1",
"Clinton",
{
value: ethers.utils.parseEther("1"),
}
);
await coffeeTxn1.wait();
expect(coffeeTxn1.hash).to.be.a("string");
});
it("Should be able to buy a coffee from 2 different accounts", async function () {
const CoffeePortal = await ethers.getContractFactory("CoffeePortal");
const coffeePortal = await CoffeePortal.deploy();
const [giver1, giver2] = await ethers.getSigners();
const coffeeTxn1 = await coffeePortal.connect(giver1).buyCoffee(
"This is the coffee #1",
"Clinton",
{
value: ethers.utils.parseEther("1"),
}
);
await coffeeTxn1.wait();
expect(coffeeTxn1.hash).to.be.a("string");
const coffeeTxn2 = await coffeePortal.connect(giver2).buyCoffee(
"This is the coffee #2",
"Jordan",
{
value: ethers.utils.parseEther("1"),
}
);
await coffeeTxn2.wait();
expect(coffeeTxn2.hash).to.be.a("string");
});
it("Should be able to get total Coffee", async function () {
const CoffeePortal = await ethers.getContractFactory("CoffeePortal");
const coffeePortal = await CoffeePortal.deploy();
const [giver1, giver2] = await ethers.getSigners();
const coffeeTxn1 = await coffeePortal.connect(giver1).buyCoffee(
"This is the coffee #1",
"Clinton",
{
value: ethers.utils.parseEther("1"),
}
);
await coffeeTxn1.wait();
expect(coffeeTxn1.hash).to.be.a("string");
const coffeeTxn2 = await coffeePortal.connect(giver2).buyCoffee(
"This is the coffee #2",
"Jordan",
{
value: ethers.utils.parseEther("1"),
}
);
await coffeeTxn2.wait();
expect(coffeeTxn2.hash).to.be.a("string");
const totalCoffee = await coffeePortal.getTotalCoffee();
expect(totalCoffee).to.equal(2);
});
it("Should be able to get All Coffee", async function () {
const CoffeePortal = await ethers.getContractFactory("CoffeePortal");
const coffeePortal = await CoffeePortal.deploy();
const [giver1, giver2] = await ethers.getSigners();
const coffeeTxn1 = await coffeePortal.connect(giver1).buyCoffee(
"This is the coffee #1",
"Clinton",
{
value: ethers.utils.parseEther("1"),
}
);
await coffeeTxn1.wait();
expect(coffeeTxn1.hash).to.be.a("string");
const coffeeTxn2 = await coffeePortal.connect(giver2).buyCoffee(
"This is the coffee #2",
"Jordan",
{
value: ethers.utils.parseEther("1"),
}
);
await coffeeTxn2.wait();
expect(coffeeTxn2.hash).to.be.a("string");
const allCoffee = await coffeePortal.getAllCoffee();
expect(allCoffee).to.be.a("array");
expect(allCoffee.length).to.equal(2);
});
});
let us proceed to deploy and test(simulating frontend test) our smart contract in a local node.
Inside the scripts folder, we will create a coffee.js file and then add the following code snippet.
const main = async () => {
// Get the example accounts we'll be working with.
const [owner, giver1, giver2] = await hre.ethers.getSigners();
const coffeeContractFactory = await hre.ethers.getContractFactory(
"CoffeePortal"
);
const coffeeContract = await coffeeContractFactory.deploy();
console.log("===========================================================");
await coffeeContract.deployed();
console.log("Coffee Contract deployed to:", coffeeContract.address);
console.log("===========================================================");
/*
* Get Owner balance
*/
let ownerBalance = await hre.ethers.provider.getBalance(
owner.address
);
console.log(
"ownerBalance: ",
hre.ethers.utils.formatEther(ownerBalance)
);
console.log("===========================================================");
/*
* Let's try to buy two coffees from 2 different accounts a coffee
*/
const coffeeTxn1 = await coffeeContract.connect(giver1).buyCoffee(
"This is the coffee #1",
"Clinton",
{
value: hre.ethers.utils.parseEther("1"),
}
);
await coffeeTxn1.wait();
console.log("===========================================================");
console.log("Coffee #1 bought by:", giver1.address);
console.log("===========================================================");
// Buy a coffee from giver2
const coffeeTxn2 = await coffeeContract.connect(giver2).buyCoffee(
"This is the coffee #2",
"Jordan",
{
value: hre.ethers.utils.parseEther("1"),
}
);
await coffeeTxn2.wait();
console.log("===========================================================");
console.log("Coffee #2 bought by:", giver2.address);
console.log("===========================================================");
/*
* Get Owner balance
*/
let ownerBalanceResult = await hre.ethers.provider.getBalance(
owner.address
);
console.log(
"ownerBalanceLater: ",
hre.ethers.utils.formatEther(ownerBalanceResult)
);
console.log("===========================================================");
let allCoffee = await coffeeContract.getAllCoffee();
console.log(allCoffee);
};
const runMain = async () => {
try {
await main();
process.exit(0);
} catch (error) {
console.log(error);
process.exit(1);
}
};
runMain();
Next, we will deploy our Defi smart contract.
npx hardhat run scripts/coffee.js --network localhost
We just wrote, test and deploy our contract. 🥳🥳🥳
Building a DApp.
See you in the next Series!!!