Webapp Testing

What This Skill Does

The Webapp Testing skill allows users to test local web applications using native Python Playwright scripts. It provides helper scripts for managing server lifecycles, enabling comprehensive testing of both static and dynamic web applications. This skill is designed for developers and QA engineers who need to automate testing of web applications during development.

When to Use

Test static HTML web applications. Test dynamic web applications. Automate web application testing. Manage server lifecycles during testing. Identify selectors for Playwright scripts. Run Playwright scripts with server management.

Key Features

Uses native Python Playwright scripts. Provides helper scripts for server management. Supports multiple servers. Offers a decision tree for choosing the right approach. Includes examples of using with_server.py. Focuses on reconnaissance-then-action approach.

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: python scripts/with_server.py --server "npm run dev" --port 5173 -- python your_automation.py

Multiple servers (e.g., backend + frontend): 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): 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

Inspect rendered DOM: page.screenshot(path='/tmp/inspect.png', full_page=True) content = page.content() page.locator('button').all()

Identify selectors from inspection results

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 automationWeb 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: python scripts/with_server.py --server "npm run dev" --port 5173 -- python your_automation.py

Multiple servers (e.g., backend + frontend): 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): 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

Inspect rendered DOM: page.screenshot(path='/tmp/inspect.png', full_page=True) content = page.content() page.locator('button').all()

Identify selectors from inspection results

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