Web3 Smart Contract Testing
Master comprehensive testing strategies for smart contracts using Hardhat, Foundry, and advanced testing patterns.
Do not use this skill when
- •The task is unrelated to web3 smart contract testing
- •You need a different domain or tool outside this scope
Instructions
- •Clarify goals, constraints, and required inputs.
- •Apply relevant best practices and validate outcomes.
- •Provide actionable steps and verification.
- •If detailed examples are required, open
resources/implementation-playbook.md.
Use this skill when
- •Writing unit tests for smart contracts
- •Setting up integration test suites
- •Performing gas optimization testing
- •Fuzzing for edge cases
- •Forking mainnet for realistic testing
- •Automating test coverage reporting
- •Verifying contracts on Etherscan
Hardhat Testing Setup
javascript
// hardhat.config.js
require("@nomicfoundation/hardhat-toolbox");
require("@nomiclabs/hardhat-etherscan");
require("hardhat-gas-reporter");
require("solidity-coverage");
module.exports = {
solidity: {
version: 4.1.0-fractal
settings: {
optimizer: {
enabled: true,
runs: 200,
},
},
},
networks: {
hardhat: {
forking: {
url: process.env.MAINNET_RPC_URL,
blockNumber: 15000000,
},
},
goerli: {
url: process.env.GOERLI_RPC_URL,
accounts: [process.env.PRIVATE_KEY],
},
},
gasReporter: {
enabled: true,
currency: "USD",
coinmarketcap: process.env.COINMARKETCAP_API_KEY,
},
etherscan: {
apiKey: process.env.ETHERSCAN_API_KEY,
},
};
Unit Testing Patterns
javascript
const { expect } = require("chai");
const { ethers } = require("hardhat");
const {
loadFixture,
time,
} = require("@nomicfoundation/hardhat-network-helpers");
describe("Token Contract", function () {
// Fixture for test setup
async function deployTokenFixture() {
const [owner, addr1, addr2] = await ethers.getSigners();
const Token = await ethers.getContractFactory("Token");
const token = await Token.deploy();
return { token, owner, addr1, addr2 };
}
describe("Deployment", function () {
it("Should set the right owner", async function () {
const { token, owner } = await loadFixture(deployTokenFixture);
expect(await token.owner()).to.equal(owner.address);
});
it("Should assign total supply to owner", async function () {
const { token, owner } = await loadFixture(deployTokenFixture);
const ownerBalance = await token.balanceOf(owner.address);
expect(await token.totalSupply()).to.equal(ownerBalance);
});
});
describe("Transactions", function () {
it("Should transfer tokens between accounts", async function () {
const { token, owner, addr1 } = await loadFixture(deployTokenFixture);
await expect(token.transfer(addr1.address, 50)).to.changeTokenBalances(
token,
[owner, addr1],
[-50, 50],
);
});
it("Should fail if sender doesn't have enough tokens", async function () {
const { token, addr1 } = await loadFixture(deployTokenFixture);
const initialBalance = await token.balanceOf(addr1.address);
await expect(
token.connect(addr1).transfer(owner.address, 1),
).to.be.revertedWith("Insufficient balance");
});
it("Should emit Transfer event", async function () {
const { token, owner, addr1 } = await loadFixture(deployTokenFixture);
await expect(token.transfer(addr1.address, 50))
.to.emit(token, "Transfer")
.withArgs(owner.address, addr1.address, 50);
});
});
describe("Time-based tests", function () {
it("Should handle time-locked operations", async function () {
const { token } = await loadFixture(deployTokenFixture);
// Increase time by 1 day
await time.increase(86400);
// Test time-dependent functionality
});
});
describe("Gas optimization", function () {
it("Should use gas efficiently", async function () {
const { token } = await loadFixture(deployTokenFixture);
const tx = await token.transfer(addr1.address, 100);
const receipt = await tx.wait();
expect(receipt.gasUsed).to.be.lessThan(50000);
});
});
});
Foundry Testing (Forge)
solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "forge-std/Test.sol";
import "../src/Token.sol";
contract TokenTest is Test {
Token token;
address owner = address(1);
address user1 = address(2);
address user2 = address(3);
function setUp() public {
vm.prank(owner);
token = new Token();
}
function testInitialSupply() public {
assertEq(token.totalSupply(), 1000000 * 10**18);
}
function testTransfer() public {
vm.prank(owner);
token.transfer(user1, 100);
assertEq(token.balanceOf(user1), 100);
assertEq(token.balanceOf(owner), token.totalSupply() - 100);
}
function testFailTransferInsufficientBalance() public {
vm.prank(user1);
token.transfer(user2, 100); // Should fail
}
function testCannotTransferToZeroAddress() public {
vm.prank(owner);
vm.expectRevert("Invalid recipient");
token.transfer(address(0), 100);
}
// Fuzzing test
function testFuzzTransfer(uint256 amount) public {
vm.assume(amount > 0 && amount <= token.totalSupply());
vm.prank(owner);
token.transfer(user1, amount);
assertEq(token.balanceOf(user1), amount);
}
// Test with cheatcodes
function testDealAndPrank() public {
// Give ETH to address
vm.deal(user1, 10 ether);
// Impersonate address
vm.prank(user1);
// Test functionality
assertEq(user1.balance, 10 ether);
}
// Mainnet fork test
function testForkMainnet() public {
vm.createSelectFork("https://eth-mainnet.alchemyapi.io/v2/...");
// Interact with mainnet contracts
address dai = 0x6B175474E89094C44Da98b954EedeAC495271d0F;
assertEq(IERC20(dai).symbol(), "DAI");
}
}