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Webapp Testing

Skills#frontend#testing

Test your local web app in a real browser with Playwright.

Anthropic's skill for checking a web app you are running locally: it drives Playwright to verify frontend behaviour, debug the UI, take screenshots and read browser logs.

Install this skill

npx skills add https://github.com/anthropics/skills --skill webapp-testing

Runs the open-source skills CLI in your own terminal. It asks which agents to add the skill to. Read what it tells your agent to do before you install it.

Download skill (.zip)

Install for your agent

  • Claude Code

    Run this in your project

    npx skills add https://github.com/anthropics/skills --skill webapp-testing -a claude-code

    Add -g to install it for every project instead.

    Or ask Claude Code to do it

    Install the "webapp-testing" skill from https://github.com/anthropics/skills for Claude Code.
Copy the skill folder (the one containing SKILL.md, with any scripts or reference files next to it) into .claude/skills/ in this project.
Before copying, show me the SKILL.md and list any scripts it includes, and wait for me to confirm.

    Or copy the folder yourself

    Unzip the download into .claude/skills/ for this project, or ~/.claude/skills/ for all your projects.

    Picked up in the current session, no restart needed.

    Claude Code skills docs
  • Claude.aiNot supported

    This skill is marked as not working in Claude.ai, usually because it needs a terminal or files that Claude.ai does not have.

    Claude.ai skills docs
  • ChatGPTNot supported

    This skill is marked as not working in ChatGPT, usually because it needs a terminal or files that ChatGPT does not have.

    ChatGPT skills docs
  • Codex

    Run this in your project

    npx skills add https://github.com/anthropics/skills --skill webapp-testing -a codex

    Add -g to install it for every project instead.

    Or ask Codex to do it

    Install the "webapp-testing" skill from https://github.com/anthropics/skills for Codex.
Copy the skill folder (the one containing SKILL.md, with any scripts or reference files next to it) into .agents/skills/ in this project.
Before copying, show me the SKILL.md and list any scripts it includes, and wait for me to confirm.

    Or copy the folder yourself

    Unzip the download into .agents/skills/ for this project, or ~/.agents/skills/ for all your projects.

    Restart Codex if the skill does not show up.

    Codex skills docs
  • Cursor

    Run this in your project

    npx skills add https://github.com/anthropics/skills --skill webapp-testing -a cursor

    Add -g to install it for every project instead.

    Or ask Cursor to do it

    Install the "webapp-testing" skill from https://github.com/anthropics/skills for Cursor.
Copy the skill folder (the one containing SKILL.md, with any scripts or reference files next to it) into .cursor/skills/ in this project.
Before copying, show me the SKILL.md and list any scripts it includes, and wait for me to confirm.

    Or copy the folder yourself

    Unzip the download into .cursor/skills/ for this project, or ~/.cursor/skills/ for all your projects.

    Run it by typing / and the skill name in chat.

    Cursor skills docs
  • GitHub Copilot

    Run this in your project

    npx skills add https://github.com/anthropics/skills --skill webapp-testing -a github-copilot

    Add -g to install it for every project instead.

    Or ask GitHub Copilot to do it

    Install the "webapp-testing" skill from https://github.com/anthropics/skills for GitHub Copilot.
Copy the skill folder (the one containing SKILL.md, with any scripts or reference files next to it) into .github/skills/ in this project.
Before copying, show me the SKILL.md and list any scripts it includes, and wait for me to confirm.

    Or copy the folder yourself

    Unzip the download into .github/skills/ for this project, or ~/.copilot/skills/ for all your projects.

    Works in Copilot CLI, the cloud agent and agent mode in VS Code and JetBrains.

    GitHub Copilot skills docs
  • Antigravity

    Run this in your project

    npx skills add https://github.com/anthropics/skills --skill webapp-testing -a antigravity

    Add -g to install it for every project instead.

    Or ask Antigravity to do it

    Install the "webapp-testing" skill from https://github.com/anthropics/skills for Antigravity.
Copy the skill folder (the one containing SKILL.md, with any scripts or reference files next to it) into .agents/skills/ in this project.
Before copying, show me the SKILL.md and list any scripts it includes, and wait for me to confirm.

    Or copy the folder yourself

    Unzip the download into .agents/skills/ for this project, or ~/.gemini/config/skills/ for all your projects.

    Antigravity skills docs
  • Gemini CLI

    Run this in your project

    npx skills add https://github.com/anthropics/skills --skill webapp-testing -a gemini-cli

    Add -g to install it for every project instead.

    Or ask Gemini CLI to do it

    Install the "webapp-testing" skill from https://github.com/anthropics/skills for Gemini CLI.
Copy the skill folder (the one containing SKILL.md, with any scripts or reference files next to it) into .gemini/skills/ in this project.
Before copying, show me the SKILL.md and list any scripts it includes, and wait for me to confirm.

    Or copy the folder yourself

    Unzip the download into .gemini/skills/ for this project, or ~/.gemini/skills/ for all your projects.

    Run /skills to check it was found.

    Gemini CLI skills docs
Installs
156K via skills.sh
GitHub
176.2K stars ↗
Last updated
10 Sept 2026

Security checks

Run by independent scanners and published on skills.sh. Their results, not a Viberation review.

  • Gen Agent Trust Hub Pass

    This toolkit, authored by a trusted developer, provides utilities for testing local web applications using Playwright. It features a server management script and several automation examples. The skill follows established patterns for development tooling, though it involves executing local commands to manage server processes as part of its intended functionality.

    21 Apr 2026

  • Socket Pass

    No alerts

    21 Apr 2026

  • Snyk Pass

    Risk: LOW · No issues

    21 Apr 2026

  • Runlayer Warning

    3/6 files flagged

    26 Feb 2026

  • ZeroLeaks Pass

    Score: 93/100 · 2 sections analyzed

    16 Apr 2026
What's inside (6 files)
  • examples/console_logging.py1K chars
  • examples/element_discovery.py1.5K chars
  • examples/static_html_automation.py953 chars
  • LICENSE.txt11.3K chars
  • scripts/with_server.py3.7K chars
  • SKILL.md3.9K chars

SKILL.md. Shown as plain text.

---
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.

**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

Key info

Pricing
Open source
Category
Skills

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