webapp-testing

Goal: Test local web applications using native Python Playwright scripts with server lifecycle management.

| Step | Action | Key Notes |

|------|--------|-----------|

| 1 | Determine approach | Static HTML: read source for selectors; Dynamic: use server helper |

| 2 | Start server | python scripts/with_server.py --server "cmd" --port N -- python script.py |

| 3 | Reconnaissance | Navigate, wait for networkidle, screenshot/inspect DOM |

| 4 | Execute actions | Use discovered selectors with Playwright API |

| 5 | Clean up | Always close browser when done |

Key Principles:

• Always wait for networkidle before inspecting DOM on dynamic apps
• Run scripts with --help first -- treat as black boxes, do not read source unless necessary
• Use sync_playwright() with headless=True for chromium

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.

```

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

```

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()

```

1. Inspect rendered DOM:

```python

page.screenshot(path='/tmp/inspect.png', full_page=True)

content = page.content()

page.locator('button').all()

```

1. Identify selectors from inspection results

1. Execute actions using discovered selectors

❌ Don't inspect the DOM before waiting for networkidle on dynamic apps

✅ Do wait for page.wait_for_load_state('networkidle') before inspection

• 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()

• 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

• Always plan and break many small todo tasks
• Always add a final review todo task to review the works done at the end to find any fix or enhancement needed