---
name: webapp-testing
description: Playwright toolkit for local webapp testing. Verify frontend, debug UI, capture screenshots, view browser logs.
license: Complete terms in LICENSE.txt
---

# Web Application Testing

Test local webapps: write native Python Playwright scripts.

**Helper Scripts Available**:
- `scripts/with_server.py` - Manages server lifecycle (multi-server support)

**Always run scripts with `--help` first.** DO NOT read source until customized solution absolutely needed. Scripts can be large — pollute context window. Call directly as black boxes.

## 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

Run `--help` first, then use 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
```

Automation script — Playwright logic only (servers 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

3. **Execute actions** using discovered selectors

## Common Pitfall

❌ **Don't** inspect DOM before `networkidle` on dynamic apps
✅ **Do** wait `page.wait_for_load_state('networkidle')` before inspection

## Best Practices

- **Use bundled scripts as black boxes** — check `scripts/` first. Handle complex workflows, no context clutter. `--help` then invoke directly.
- Use `sync_playwright()` for synchronous scripts
- Always close browser when done
- Use descriptive selectors: `text=`, `role=`, CSS selectors, IDs
- Add waits: `page.wait_for_selector()` or `page.wait_for_timeout()`

## Reference Files

- **examples/** - Common patterns:
  - `element_discovery.py` - Discovering buttons, links, inputs
  - `static_html_automation.py` - Using file:// URLs for local HTML
  - `console_logging.py` - Capturing console logs during automation