# webapp-testing

> 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.

- Author: Crumbgrabber
- Repository: Crumbgrabber/llm_system_template_agents_skills_patterns_tools_prompts
- Version: 20251228142431
- Stars: 1
- Forks: 0
- Last Updated: 2026-02-06
- Source: https://github.com/Crumbgrabber/llm_system_template_agents_skills_patterns_tools_prompts
- Web: https://mule.run/skillshub/@@Crumbgrabber/llm_system_template_agents_skills_patterns_tools_prompts~webapp-testing:20251228142431

---

---
name: webapp-testing
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.
license: Complete terms in LICENSE.txt
---

# Web Application Testing

To test local web applications, write native Python Playwright scripts. Start required servers yourself (frontend/backend) before running automation.

## 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 → Start the server (backend/frontend) in a separate shell
        │
        └─ 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: Starting a server and running Playwright

Start your app servers in separate shell(s), then run automation:
```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

- **Keep automation focused** - Prefer small, task-focused Playwright scripts and start/stop servers explicitly as needed.
- 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