Skip to content
web3-testing · wshobson-agents · Flowy
Test smart contracts comprehensively using Hardhat and Foundry with unit tests, integration tests, and mainnet forking. Use when testing Solidity contracts, setting up blockchain test suites, or validating DeFi protocols.
One skill from wshobson-agents .
$ npx -y skills add wshobson/agents --skill web3-testing --agent claude-codeInstalls just this skill. Get the whole plugin for auto-invocation.
⚡ How it fires
How this skill gets triggered: by you, by Claude, or both.
Fires itself Claude auto-loads it when your prompt matches the work. You can call it Invoke it directly when you want it. Slash command /web3-testing👁️ Context preview
The summary Claude sees to decide when to auto-load this skill.
Test smart contracts comprehensively using Hardhat and Foundry with unit tests, integration tests, and mainnet forking. Use when testing Solidity contracts, setting up blockchain test suites, or validating DeFi protocols. 📦 Ships with wshobson-agents
</> SKILL.md
web3-testing.SKILL.md
---
name : web3-testing
description : Test smart contracts comprehensively using Hardhat and Foundry with unit tests, integration tests, and mainnet forking. Use when testing Solidity contracts, setting up blockchain test suites, or validating DeFi protocols.
---
# Web3 Smart Contract Testing
Master comprehensive testing strategies for smart contracts using Hardhat, Foundry, and advanced testing patterns.
## When to Use This Skill
- 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: "0.8.19",
settings: {
optimizer: {
enabled: true,
runs: 200,
Flowy AI Flows that just work. Hand-picked Claude Code plugins that fire the right skill as you prompt.
},
},
},
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");
}
}
```
## Advanced Testing Patterns
### Snapshot and Revert
```javascript
describe("Complex State Changes", function () {
let snapshotId;
beforeEach(async function () {
snapshotId = await network.provider.send("evm_snapshot");
});
afterEach(async function () {
await network.provider.send("evm_revert", [snapshotId]);
});
it("Test 1", async function () {
// Make state changes
});
it("Test 2", async function () {
// State reverted, clean slate
});
});
```
### Mainnet Forking
```javascript
describe("Mainnet Fork Tests", function () {
let uniswapRouter, dai, usdc;
before(async function () {
await network.provider.request({
method: "hardhat_reset",
params: [
{
forking: {
jsonRpcUrl: process.env.MAINNET_RPC_URL,
blockNumber: 15000000,
},
},
],
});
// Connect to existing mainnet contracts
uniswapRouter = await ethers.getContractAt(
"IUniswapV2Router",
"0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D",
);
dai = await ethers.getContractAt(
"IERC20",
"0x6B175474E89094C44Da98b954EedeAC495271d0F",
);
});
it("Should swap on Uniswap", async function () {
// Test with real Uniswap contracts
});
});
```
### Impersonating Accounts
```javascript
it("Should impersonate whale account", async function () {
const whaleAddress = "0x...";
await network.provider.request({
method: "hardhat_impersonateAccount",
params: [whaleAddress],
});
const whale = await ethers.getSigner(whaleAddress);
// Use whale's tokens
await dai
.connect(whale)
.transfer(addr1.address, ethers.utils.parseEther("1000"));
});
```
## Additional patterns and templates
More detailed templates and worked examples live in `references/details.md`. Read that file for the full pattern library.
© 2026 Flowy · Free and open source
Built for Claude Code · Not affiliated with Anthropic
