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 helper script source unless customization is absolutely required.

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 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

Run help first, then execute:

Single server

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

Multiple servers

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

Playwright Pattern

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')
    # ... automation logic
    browser.close()

Reconnaissance-Then-Action

1. Inspect rendered DOM
2. Identify selectors from observed page state
3. Execute actions with discovered selectors

Common Pitfall

• Do not inspect dynamic app DOM before networkidle
• Do wait for page.wait_for_load_state('networkidle') first

Best Practices

• Use bundled scripts as black boxes
• Use sync_playwright() for synchronous scripts
• Always close browser sessions
• Prefer descriptive selectors (text=, role=, CSS, IDs)
• Add explicit waits where needed

Reference Files

• examples/element_discovery.py
• examples/static_html_automation.py
• examples/console_logging.py