Testing with ethers.js in Blockchain / Solidity - Mini Project: Build & Apply

Testing with ethers.js

📖 Scenario: You are building a simple smart contract that stores a number. You want to write tests using ethers.js to check if the contract works correctly.

🎯 Goal: Write a test script using ethers.js that deploys the contract, sets a number, and checks if the stored number is correct.

📋 What You'll Learn

Create a variable called SimpleStorage to get the contract factory

Create a variable called simpleStorage to deploy the contract

Create a variable called tx to store the transaction when setting the number

Use await tx.wait() to wait for the transaction to be mined

Use const storedNumber = await simpleStorage.retrieve() to get the stored number

Use console.log(storedNumber.toString()) to print the stored number

💡 Why This Matters

🌍 Real World

Testing smart contracts before deploying them to the blockchain helps avoid costly mistakes and bugs.

💼 Career

Blockchain developers use ethers.js and testing frameworks to ensure their contracts work correctly and securely.

1

Setup ethers.js and get the contract factory

Write const SimpleStorage = await ethers.getContractFactory('SimpleStorage') to get the contract factory for SimpleStorage.

Blockchain / Solidity

# Your code here

Need a hint?

Use ethers.getContractFactory with the contract name 'SimpleStorage'.

2

Deploy the contract

Write const simpleStorage = await SimpleStorage.deploy() to deploy the contract and store it in simpleStorage.

Blockchain / Solidity

const SimpleStorage = await ethers.getContractFactory('SimpleStorage')
# Your code here

Need a hint?

Call deploy() on SimpleStorage and assign it to simpleStorage.

3

Set a number in the contract

Write const tx = await simpleStorage.store(42) to call the store function with the number 42 and save the transaction in tx. Then write await tx.wait() to wait for the transaction to be mined.

Blockchain / Solidity

const SimpleStorage = await ethers.getContractFactory('SimpleStorage')
const simpleStorage = await SimpleStorage.deploy()
# Your code here

Need a hint?

Call store(42) on simpleStorage and wait for the transaction to complete.

4

Retrieve and print the stored number

Write const storedNumber = await simpleStorage.retrieve() to get the stored number. Then write console.log(storedNumber.toString()) to print it.

Blockchain / Solidity

const SimpleStorage = await ethers.getContractFactory('SimpleStorage')
const simpleStorage = await SimpleStorage.deploy()
const tx = await simpleStorage.store(42)
await tx.wait()
# Your code here

Need a hint?

Call retrieve() on simpleStorage and print the result as a string.