playwright-core

# Playwright Core Testing > Opinionated, production-tested Playwright guidance — every pattern includes when (and when _not_) to use it. **46 reference guides** covering the full Playwright testing surface: selectors, assertions, fixtures, network mocking, auth, visual regression, accessibility, API testing, debugging, and more — with TypeScript and JavaScript examples throughout. ## Golden Rules 1. **`getByRole()` over CSS/XPath** — resilient to markup changes, mirrors how users see the page 2. **Never `page.waitForTimeout()`** — use `expect(locator).toBeVisible()` or `page.waitForURL()` 3. **Web-first assertions** — `expect(locator)` auto-retries; `expect(await locator.textContent())` does not 4. **Isolate every test** — no shared state, no execution-order dependencies 5. **`baseURL` in config** — zero hardcoded URLs in tests 6. **Retries: `2` in CI, `0` locally** — surface flakiness where it matters 7. **Traces: `'on-first-retry'`** — rich debugging artifacts without CI slowdown 8. **Fixtures over globals** — share state via `test.extend()`, not module-level variables 9. **One behavior per test** — multiple related `expect()` calls are fine 10. **Mock external services only** — never mock your own app; mock third-party APIs, payment gateways, email ## Guide Index ### Writing Tests | What you're doing | Guide | Deep dive | | -------------------------- | ------------------------------------------------------ | -------------------------------------------------- | | Choosing selectors | [locators.md](locators.md) | [locator-strategy.md](locator-strategy.md) | | Assertions & waiting | [assertions-and-waiting.md](assertions-and-waiting.md) | | | Organizing test suites | [test-organization.md](test-organization.md) | [test-architecture.md](test-architecture.md) | | Playwright config | [configuration.md](configuration.md) | | | Fixtures & hooks | [fixtures-and-hooks.md](fixtures-and-hooks.md) | | | Test data | [test-data-management.md](test-data-management.md) | | | Auth & login | [authentication.md](authentication.md) | [auth-flows.md](auth-flows.md) | | API testing (REST/GraphQL) | [api-testing.md](api-testing.md) | | | Visual regression | [visual-regression.md](visual-regression.md) | | | Accessibility | [accessibility.md](accessibility.md) | | | Mobile & responsive | [mobile-and-responsive.md](mobile-and-responsive.md) | | | Component testing | [component-testing.md](component-testing.md) | | | Network mocking | [network-mocking.md](network-mocking.md) | [when-to-mock.md](when-to-mock.md) | | Forms & validation | [forms-and-validation.md](forms-and-validation.md) | | | File uploads/downloads | [file-operations.md](file-operations.md) | [file-upload-download.md](file-upload-download.md) | | Error & edge cases | [error-and-edge-cases.md](error-and-edge-cases.md) | | | CRUD flows | [crud-testing.md](crud-testing.md) | | | Drag and drop | [drag-and-drop.md](drag-and-drop.md) | | | Search & filter UI | [search-and-filter.md](search-and-filter.md) | | ### Debugging & Fixing | Problem | Guide | | -------------------------- | ---------------------------------------- | | General debugging workflow | [debugging.md](debugging.md) | | Specific error message | [error-index.md](error-index.md) | | Flaky / intermittent tests | [flaky-tests.md](flaky-tests.md) | | Common beginner mistakes | [common-pitfalls.md](common-pitfalls.md) | ### Framework Recipes | Framework | Guide | | ----------------------------------- | ------------------------ | | Next.js (App Router + Pages Router) | [nextjs.md](nextjs.md) | | React (CRA, Vite) | [react.md](react.md) | | Vue 3 / Nuxt | [vue.md](vue.md) | | Angular | [angular.md](angular.md) | ### Specialized Topics | Topic | Guide | | ------------------------------------------ | ------------------------------------------------------------------ | | Multi-user & collaboration | [multi-user-and-collaboration.md](multi-user-and-collaboration.md) | | WebSockets & real-time | [websockets-and-realtime.md](websockets-and-realtime.md) | | Browser APIs (geo, clipboard, permissions) | [browser-apis.md](browser-apis.md) | | iframes & Shadow DOM | [iframes-and-shadow-dom.md](iframes-and-shadow-dom.md) | | Canvas & WebGL | [canvas-and-webgl.md](canvas-and-webgl.md) | | Service workers & PWA | [service-workers-and-pwa.md](service-workers-and-pwa.md) | | Electron apps | [electron-testing.md](electron-testing.md) | | Browser extensions | [browser-extensions.md](browser-extensions.md) | | Security testing | [security-testing.md](security-testing.md) | | Performance & benchmarks | [performance-testing.md](performance-testing.md) | | i18n & localization | [i18n-and-localization.md](i18n-and-localization.md) | | Multi-tab & popups | [multi-context-and-popups.md](multi-context-and-popups.md) | | Clock & time mocking | [clock-and-time-mocking.md](clock-and-time-mocking.md) | | Third-party integrations | [third-party-integrations.md](third-party-integrations.md) | ### Architecture Decisions | Question | Guide | | ------------------------ | -------------------------------------------- | | Which locator strategy? | [locator-strategy.md](locator-strategy.md) | | E2E vs component vs API? | [test-architecture.md](test-architecture.md) | | Mock vs real services? | [when-to-mock.md](when-to-mock.md) |