# 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.

- Skill: `bananayong/webapp-testing` (Agent Skill, multi-file: 6 files)
- Install (CLI): `npx skillmds@latest add bananayong/webapp-testing`
- Raw SKILL.md: https://api.skillmd.com/api/skills/bananayong/webapp-testing/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- License: Complete terms in LICENSE.txt
- Author: bananayong (https://skillmd.com/u/bananayong)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/bananayong/webapp-testing

---


# Web Application Testing

Use this skill for local web application verification. Prefer `playwright-cli` for quick interactive checks, and use Python Playwright scripts when you need custom assertions or server lifecycle orchestration.

**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 absolutely necessary. These scripts can be large and pollute context, so use them as black-box utilities first.

## Preferred Paths

1. Fast exploratory verification (recommended): `playwright-cli`
```bash
playwright-cli open http://localhost:5173 --browser=chromium
playwright-cli snapshot
playwright-cli click e12
playwright-cli console
playwright-cli close
```

2. Repeatable scripted testing with custom logic: Python + Playwright (`scripts/with_server.py`)

## Decision Tree: Choosing Your Approach

```
User task → Need quick navigation/selector validation/debug output?
    ├─ Yes → Use playwright-cli session first
    │         ├─ Enough for task → finish
    │         └─ Need custom assertions/complex flow → Python path below
    │
    └─ No → 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** - Consider whether one of the scripts in `scripts/` solves the task before writing custom orchestration.
- Prefer `playwright-cli` for lightweight exploration and quick debugging loops.
- 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