Project Vandal: UI Mutation Testing Engine

Project Vandal is a lightweight, non-LLM UI mutation testing engine integrated with Playwright. It allows you to sabotage your UI in subtle ways to verify if your end-to-end tests are resilient and capable of detecting regressions.

Features

• Mutation Strategies:
  • stealth_disable: Disables pointer events on elements, making them unclickable while remaining visually present.
  • ghost_element: Makes elements invisible and unclickable.
  • data_sabotage: Replaces text or input values with junk data.
  • logic_sabotage: Prevents event propagation (e.g., stopping click handlers from firing).
• Playwright Integration: Easy-to-use context manager (Vandal) for wrapping test logic.
• Reporting: Automated mutation report showing which "mutants" were killed (detected by tests) or survived.
• Detailed Guide: See TESTER_GUIDE.md for advanced usage and customization.

Project Structure

• core.py: The heart of the mutation engine (JavaScript-based strategies).
• playwright_ext.py: Playwright wrapper and context manager.
• demo_vandal.py: A demonstration script showing Vandal in action.
• vandal_demo_app.html: A simple demo application for testing.

Installation

Ensure you have Playwright installed:

# Install the engine from PyPI
pip install project-vandal

# Or clone for local development
git clone https://github.com/godhiraj-code/vandal.git
cd vandal
pip install .

# Setup Playwright
playwright install chromium

Usage

You can use the Vandal class as a context manager in your Playwright tests:

from vandal import Vandal

async with Vandal(page) as v:
    # Aply a mutation to an element
    await v.apply_mutation("stealth_disable", "#login-btn")
    
    # Run your test logic
    await page.click("#login-btn")
    
    # Assert the outcome
    assert await page.inner_text("#msg") == "Success"

Running the Demo

The project includes a demo script that tests a simple login button.

Headless Mode

PYTHONPATH="." python demo_vandal.py --headless

PYTHONPATH="." python demo_vandal.py --headed

In headed mode, the script includes a slow_mo delay and holds the browser open for 5 seconds after completion so you can see the results.

Why "Vandal"?

Unlike traditional mutation testing that modifies source code, Project Vandal sabotages the UI layer directly in the browser. This is particularly effective for catching:

Note

Project Vandal is an open-source research initiative by Dhiraj Das | Automation Architect.

• CSS regressions that block interactions.
• Event listener bugs.
• Data binding failures.