web3-testing Skill (wshobson) for Claude: What It Does and How to Install It

Helps Claude test Solidity smart contracts with Hardhat and Foundry, including fuzzing, mainnet forking, gas reports and coverage.

Installs: 11K; on skills.sh
Stars: 42.1K; on GitHub
Files: 1; besides SKILL.md
Updated: Oct 2026; last repo commit

This is a testing guide for Claude, from wshobson's agents collection. SKILL.md has a Hardhat config, unit test patterns with fixtures, Foundry tests with fuzzing and cheatcodes, and advanced patterns: snapshot and revert, mainnet forking and impersonating accounts. references/details.md adds gas optimization testing, coverage reporting, Etherscan verification and a CI workflow.

It loads when you test Solidity contracts or set up a blockchain test suite. It bundles no scripts. The examples read RPC URLs and a private key from environment variables, so keep real keys out of the chat and out of committed files.

Good for

Solidity developers writing unit and integration tests
DeFi teams that test against forked mainnet state
Teams that want gas reports, coverage and Etherscan verification in CI

Install web3-testing

Claude Code

Copy this prompt.

Install the web3-testing skill in Claude Code. Run this command:

/plugin marketplace add wshobson/agents
/plugin install blockchain-web3@claude-code-workflows

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Pick one route. The plugin routes install the whole blockchain-web3 plugin: 1 agent, 0 commands and 4 skills (counted from the plugin folder in the repo tree, which has no hooks or MCP config files). The skills-only routes install just this skill, with no agents or commands. The skill needs a Hardhat or Foundry project of your own. Its example config reads RPC URLs, a private key and API keys from environment variables.

From the project README. Source.

What's in the skill

When it loads

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.

Sections in SKILL.md

When to Use This Skill
Hardhat Testing Setup
Unit Testing Patterns
Foundry Testing (Forge)
Advanced Testing Patterns
Snapshot and Revert
Mainnet Forking
Impersonating Accounts
Additional patterns and templates

Key facts

Author: wshobson (repo owner)
License: MIT
Installs on skills.sh: 10,988 (Nov 2, 2026)
GitHub stars: 42,081 for the whole wshobson/agents repo (Nov 2, 2026)
Last repo commit: Oct 30, 2026
What it includes: 2 files including SKILL.md: references/details.md holds gas, coverage, verification and CI examples (no scripts)
Needs: A Hardhat or Foundry project. The Hardhat config reads MAINNET_RPC_URL, GOERLI_RPC_URL, PRIVATE_KEY, COINMARKETCAP_API_KEY and ETHERSCAN_API_KEY
Part of: The blockchain-web3 plugin in wshobson/agents. Counted from the plugin folder: 1 agent, 0 commands and 4 skills
Works in: Claude Code, Codex CLI, Cursor, OpenCode, Antigravity CLI, GitHub Copilot and Pi, per the README. Skills-only installers ask which tool you use

What it includes

hardhat.config.js with gas reporter, coverage and Etherscan
Sets Solidity 0.8.19, the optimizer, mainnet forking, a Goerli network and plugin imports.
Try: “Write Hardhat tests for my ERC-20 token, including events and reverts.”
Write · Hardhat testing setup
Hardhat tests with loadFixture for deployment, transfers, events and time
Examples check owner and supply, token balance changes, emitted events, time travel and a gas ceiling.
Write · Unit testing patterns
forge-std tests with fuzzing and cheatcodes
Uses vm.prank, vm.expectRevert, vm.assume, vm.deal and a fuzz test, plus a createSelectFork mainnet fork test.
Write · Foundry tests
Reset chain state between tests with evm_snapshot
Takes a snapshot before each test and reverts after it.
Write · Snapshot and revert
Run tests against real mainnet contracts via hardhat_reset
Forks mainnet at a block number from MAINNET_RPC_URL and talks to Uniswap and DAI contracts.
Write · Mainnet forking
hardhat_impersonateAccount to act as another address
Lets a test move tokens from another address on a local fork.
Write · Impersonating accounts
Gas tests, npx hardhat coverage and npx hardhat verify (details.md)
The verify command targets a network and a contract address with constructor arguments.
Runs code · Gas, coverage and verification
GitHub Actions job that compiles, tests and covers (details.md)
Runs npm install, npx hardhat compile, test and coverage, then uploads to Codecov.
Runs code · CI workflow

From the official docs

Permissions

Medium risk

The main risk is a private key or RPC key leaking, or a command touching a live network. Use a test-only key, keep it in environment variables and review each command.

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

The example config uses a private key
hardhat.config.js passes process.env.PRIVATE_KEY as an account for the Goerli network. Use a test-only key, keep it in an environment variable and do not commit it. github.com
The verify command publishes to Etherscan
details.md shows npx hardhat verify --network mainnet with a contract address and constructor arguments, and the config holds an Etherscan API key. Only run it for contracts you mean to publish. github.com
Forking and impersonation hit live RPC endpoints
The fork examples read MAINNET_RPC_URL and use real mainnet contract addresses such as the Uniswap router and DAI. Check which RPC endpoint and block number your tests point at. github.com
The plugin route installs more than this skill
The blockchain-web3 plugin has 4 skills, 1 agent and 0 commands. The repo tree shows no hooks or MCP config files in its folder. The skills-only routes install only this skill. github.com

Security advisories

No published security advisories as of Nov 2, 2026.

Technical details

Turning on read-only	No read-only mode. Use version control.
Talks to	Your mainnet and Goerli RPC providers, and eth-mainnet.alchemyapi.io, the URL hard-coded in the Foundry fork example. Etherscan, when you run the verify command. Codecov, in the CI example
Sign-in and keys	The examples read keys from environment variables such as PRIVATE_KEY, ETHERSCAN_API_KEY and COINMARKETCAP_API_KEY. SKILL.md does not say where you store them.
Scopes	Claude writes contract tests and config in your project when you ask The Hardhat config example reads PRIVATE_KEY, RPC URLs and API keys (including a CoinMarketCap key for the gas reporter) from environment variables The examples run npx hardhat compile, test, coverage and verify, and npm install in CI

Questions

What does the web3-testing skill do?

It gives Claude patterns for testing smart contracts. Claude uses it to write Hardhat and Foundry tests, fuzz inputs, fork mainnet and set up coverage and CI.

How do I install web3-testing?

Use the install box at the top of this page. It lists the plugin route and two skills-only commands: npx skills add wshobson/agents --skill web3-testing and gh skill install wshobson/agents web3-testing (GitHub CLI 2.90 or later). The skills-only commands skip the plugin's agents and commands.

Does it need API keys or a wallet key?

The example Hardhat config reads MAINNET_RPC_URL, GOERLI_RPC_URL, PRIVATE_KEY, COINMARKETCAP_API_KEY and ETHERSCAN_API_KEY from the environment. Use a throwaway test key, never one that holds real funds.

Does it send transactions to a real network?

The examples fork mainnet locally. The config also lists a Goerli network with an account key, and details.md has an npx hardhat verify command for mainnet, which publishes contract details to Etherscan. Check the network before you run anything.

Hardhat or Foundry?

It covers both. Hardhat examples are JavaScript with Chai, and Foundry examples are Solidity tests that import forge-std.

Is it safe?

Installing it adds a guide and one reference file, with no scripts. The examples reference a private key, RPC URLs and a verify command, so keep keys in environment variables, never paste them into the chat, and review each command before Claude runs it.

Is this skill from Anthropic?

No. It is in wshobson/agents, a community collection. The skill sits in the blockchain-web3 plugin there.

Should I install the whole blockchain-web3 plugin?

Only if you want the rest. The README documents a plugin route for Claude Code and Codex. The plugin folder holds 4 skills, 1 agent and 0 commands, and the repo tree shows no hooks or MCP config files in it.

Information

updated Nov 2, 2026

Repository: wshobson/agents
Folder: plugins/blockchain-web3/skills/web3-testing

wshobson/agents skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 4

web3-testing SKILL.md · github.com
wshobson/agents README · github.com
blockchain-web3 plugin.json · github.com
web3-testing details.md · github.com