Playwright Best Practices

CLI Context: Prevent Context Overflow

When running Playwright tests from Claude Code or any CLI agent, always use minimal reporters to prevent verbose output from consuming the context window.

Use --reporter=line or --reporter=dot for CLI test runs. Configure playwright.config.ts to default to minimal reporters when CI or CLAUDE env vars are set — see playwright-patterns.md for the config snippet.

Locator Priority (Most to Least Resilient)

Always prefer user-facing attributes:

1. page.getByRole('button', { name: 'Submit' }) — accessibility roles
2. page.getByLabel('Email') — form control labels
3. page.getByPlaceholder('Search...') — input placeholders
4. page.getByText('Welcome') — visible text (non-interactive)
5. page.getByAltText('Logo') — image alt text
6. page.getByTitle('Settings') — title attributes
7. page.getByTestId('submit-btn') — explicit test contracts
8. CSS/XPath — last resort, avoid

Core Rules

• Web-first assertions: always await expect(locator).toBeVisible(), never expect(await locator.isVisible()).toBe(true) — web-first matchers auto-wait and retry
• Test isolation: each test creates its own data; never share state between tests
• Auth state reuse: save authenticated state via setup project + storageState; never log in via UI in every test
• Fixtures over beforeEach: fixtures encapsulate setup + teardown, run on-demand, and compose

Anti-Patterns

• page.waitForTimeout(ms) — use auto-waiting locators instead
• page.locator('.class') — use role/label/testid
• XPath selectors — fragile, use user-facing attributes
• Shared state between tests — each test creates own data
• UI login in every test — use setup project + storageState
• Manual assertions without await — use web-first assertions
• Hardcoded waits — rely on Playwright's auto-waiting
• Default reporter in CI/agent — use --reporter=line or --reporter=dot

Checklist

• [ ] Locators use role/label/testid, not CSS classes or XPath
• [ ] All assertions use await expect() web-first matchers
• [ ] Page objects define locators in constructor
• [ ] No page.waitForTimeout() — use auto-waiting
• [ ] Tests isolated — no shared state
• [ ] Auth state reused via setup project
• [ ] Network mocks set up before navigation
• [ ] Test data created per-test or via fixtures
• [ ] Debug logging added for complex flows
• [ ] Minimal reporter (line/dot) used in CI/agent contexts

See playwright-patterns.md for Page Object Model, fixtures, network mocking, and configuration examples.