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Playwright Best Practices

Tips for getting the most out of Agent Mantis's Playwright foundation.

Use stable selectors​

Prefer selectors based on:

  • data-testid attributes
  • ARIA roles and labels
  • Text content

Avoid selectors based on:

  • CSS class names (change frequently)
  • DOM structure (brittle)
  • Auto-generated IDs

Keep tests independent​

Each workflow should:

  • Start from a clean state
  • Not depend on other workflows
  • Clean up after itself when possible

Handle dynamic content​

  • Use assertions to wait for content to appear
  • Avoid fixed delays (sleep) — rely on auto-waiting
  • Account for loading spinners and skeleton screens