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Skill

webapp-testing

by anthropics

AI Summary

A Playwright-based toolkit for testing local web applications, enabling developers to verify frontend functionality, debug UI behavior, and capture browser diagnostics. Essential for AI coding assistants building and validating web applications.

Install

Copy this and paste it into Claude Code, Cursor, or any AI assistant:

I want to install the "webapp-testing" skill in my project.

Please run this command in my terminal:
# Install skill into your project (6 files)
mkdir -p .claude/skills/webapp-testing && curl --retry 3 --retry-delay 2 --retry-all-errors -o .claude/skills/webapp-testing/SKILL.md "https://raw.githubusercontent.com/anthropics/skills/main/skills/webapp-testing/SKILL.md" && curl --retry 3 --retry-delay 2 --retry-all-errors -o .claude/skills/webapp-testing/LICENSE.txt "https://raw.githubusercontent.com/anthropics/skills/main/skills/webapp-testing/LICENSE.txt" && mkdir -p .claude/skills/webapp-testing/examples && curl --retry 3 --retry-delay 2 --retry-all-errors -o .claude/skills/webapp-testing/examples/console_logging.py "https://raw.githubusercontent.com/anthropics/skills/main/skills/webapp-testing/examples/console_logging.py" && mkdir -p .claude/skills/webapp-testing/examples && curl --retry 3 --retry-delay 2 --retry-all-errors -o .claude/skills/webapp-testing/examples/element_discovery.py "https://raw.githubusercontent.com/anthropics/skills/main/skills/webapp-testing/examples/element_discovery.py" && mkdir -p .claude/skills/webapp-testing/examples && curl --retry 3 --retry-delay 2 --retry-all-errors -o .claude/skills/webapp-testing/examples/static_html_automation.py "https://raw.githubusercontent.com/anthropics/skills/main/skills/webapp-testing/examples/static_html_automation.py" && mkdir -p .claude/skills/webapp-testing/scripts && curl --retry 3 --retry-delay 2 --retry-all-errors -o .claude/skills/webapp-testing/scripts/with_server.py "https://raw.githubusercontent.com/anthropics/skills/main/skills/webapp-testing/scripts/with_server.py"

Then restart Claude Code (or reload the window in Cursor) so the skill is picked up.

Description

Toolkit for interacting with and testing local web applications using Playwright. Supports verifying frontend functionality, debugging UI behavior, capturing browser screenshots, and viewing browser logs.

Web Application Testing

To test local web applications, write native Python Playwright scripts. Helper Scripts Available: • scripts/with_server.py - Manages server lifecycle (supports multiple servers) Always run scripts with --help first to see usage. DO NOT read the source until you try running the script first and find that a customized solution is abslutely necessary. These scripts can be very large and thus pollute your context window. They exist to be called directly as black-box scripts rather than ingested into your context window.

Decision Tree: Choosing Your Approach

` User task → Is it static HTML? ├─ Yes → Read HTML file directly to identify selectors │ ├─ Success → Write Playwright script using selectors │ └─ Fails/Incomplete → Treat as dynamic (below) │ └─ No (dynamic webapp) → Is the server already running? ├─ No → Run: python scripts/with_server.py --help │ Then use the helper + write simplified Playwright script │ └─ Yes → Reconnaissance-then-action: • Navigate and wait for networkidle • Take screenshot or inspect DOM • Identify selectors from rendered state • Execute actions with discovered selectors `

Example: Using with_server.py

To start a server, run --help first, then use the helper: Single server: `bash python scripts/with_server.py --server "npm run dev" --port 5173 -- python your_automation.py ` Multiple servers (e.g., backend + frontend): `bash python scripts/with_server.py \ --server "cd backend && python server.py" --port 3000 \ --server "cd frontend && npm run dev" --port 5173 \ -- python your_automation.py ` To create an automation script, include only Playwright logic (servers are managed automatically): `python from playwright.sync_api import sync_playwright with sync_playwright() as p: browser = p.chromium.launch(headless=True) # Always launch chromium in headless mode page = browser.new_page() page.goto('http://localhost:5173') # Server already running and ready page.wait_for_load_state('networkidle') # CRITICAL: Wait for JS to execute # ... your automation logic browser.close() `

Reconnaissance-Then-Action Pattern

• Inspect rendered DOM: `python page.screenshot(path='/tmp/inspect.png', full_page=True) content = page.content() page.locator('button').all() ` • Identify selectors from inspection results • Execute actions using discovered selectors

Discussion

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Works With

Claude Code