claude-native-webapp-testing

# 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: 1. Navigate and wait for networkidle 2. Take screenshot or inspect DOM 3. Identify selectors from rendered state 4. 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 1. **Inspect rendered DOM**: ```python page.screenshot(path='/tmp/inspect.png', full_page=True) content = page.content() page.locator('button').all() ``` 2. **Identify selectors** from inspection results 3. **Execute actions** using discovered selectors ## Common Pitfall ❌ **Don't** inspect the DOM before waiting for `networkidle` on dynamic apps ✅ **Do** wait for `page.wait_for_load_state('networkidle')` before inspection ## Best Practices - **Use bundled scripts as black boxes** - To accomplish a task, consider whether one of the scripts available in `scripts/` can help. These scripts handle common, complex workflows reliably without cluttering the context window. Use `--help` to see usage, then invoke directly. - Use `sync_playwright()` for synchronous scripts - Always close the browser when done - Use descriptive selectors: `text=`, `role=`, CSS selectors, or IDs - Add appropriate waits: `page.wait_for_selector()` or `page.wait_for_timeout()` ## Reference Files - **examples/** - Examples showing common patterns: - `element_discovery.py` - Discovering buttons, links, and inputs on a page - `static_html_automation.py` - Using file:// URLs for local HTML - `console_logging.py` - Capturing console logs during automation