Webapp Testing

Web Application Testing

Test web applications using Python Playwright scripts.

Decision Tree

User task → Is it static HTML?
    ├─ Yes → Read HTML file directly for selectors
    │         └─ Write Playwright script
    │
    └─ No (dynamic webapp) → Is server already running?
        ├─ No → Start server first, then test
        │
        └─ 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

Basic Playwright Script

from playwright.sync_api import sync_playwright

with sync_playwright() as p:
    browser = p.chromium.launch(headless=True)
    page = browser.new_page()
    page.goto('http://localhost:5173')
    page.wait_for_load_state('networkidle')  # CRITICAL: Wait for JS
    
    # Reconnaissance
    page.screenshot(path='/tmp/inspect.png', full_page=True)
    
    # Actions
    page.click('button#submit')
    
    browser.close()

Reconnaissance Pattern

1. Inspect DOM:

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

2. Identify selectors from results

3. Execute actions with discovered selectors

Common Pitfall

❌ Inspect DOM before waiting for networkidle ✅ Always page.wait_for_load_state('networkidle') first

Best Practices

• Use sync_playwright() for synchronous scripts
• Always close browser when done
• Use descriptive selectors: text=, role=, CSS, IDs
• Add waits: wait_for_selector(), wait_for_timeout()
• Launch chromium in headless=True mode

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