Test web applications using Playwright with screenshots and assertions
Catalog skill by anthropic: Test web applications using Playwright with screenshots and assertions Install into Cursor, Claude, Codex, or VS Code from this page or review the source for Web App Testing.
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/plugin install document-skills@anthropic-agent-skills
Install guides: Cursor skills, Claude Code skills, Codex skills, or VS Code Copilot skills.
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.
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:
1. Navigate and wait for networkidle
2. Take screenshot or inspect DOM
3. Identify selectors from rendered state
4. Execute actions with discovered selectors
To start a server, run --help first, then use the helper:
Single server:
python scripts/with_server.py --server "npm run dev" --port 5173 -- python your_automation.py
Multiple servers (e.g., backend + frontend):
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):
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()
Inspect rendered DOM:
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
❌ Don't inspect the DOM before waiting for networkidle on dynamic apps
✅ Do wait for page.wait_for_load_state('networkidle') before inspection
scripts/ can help. These scripts handle common, complex workflows reliably without cluttering the context window. Use --help to see usage, then invoke directly.sync_playwright() for synchronous scriptstext=, role=, CSS selectors, or IDspage.wait_for_selector() or page.wait_for_timeout()element_discovery.py - Discovering buttons, links, and inputs on a pagestatic_html_automation.py - Using file:// URLs for local HTMLconsole_logging.py - Capturing console logs during automation