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) |