E2E Testing
Overview
Covers E2E test architecture and patterns using Playwright — how to structure test suites, organize tests, and apply proven patterns for authentication, mocking, visual regression, accessibility auditing, and CI parallelism. Focuses on the WHY and WHEN of test patterns rather than Playwright API specifics.
When to use: Designing test suite architecture, structuring Page Object Models, planning CI sharding strategies, setting up authentication flows, organizing tests with tags and annotations, implementing visual regression workflows, mocking network requests, auditing accessibility.
When NOT to use: Unit testing (use Vitest/Jest), API-only testing (use integration tests), component testing in isolation (use component test runners). For Playwright API details, browser automation, scraping, or troubleshooting Playwright errors, use the playwright skill.
Quick Reference
| Pattern | API/Tool | Key Points |
|---|---|---|
| Role-based locators | getByRole, getByText, getByLabel | Preferred over CSS/XPath selectors |
| Page Object Model | Classes in tests/pages/ | Encapsulate all page-specific locators and actions |
| Authentication | storageState + setup projects | Authenticate once, reuse across tests |
| Visual regression | expect(page).toHaveScreenshot() | Mask dynamic content to prevent flakes |
| Accessibility audit | AxeBuilder from @axe-core/playwright | .withTags() + .analyze() on key flows |
| Trace debugging | trace: 'on-first-retry' | Full DOM snapshots, network logs, and timeline |
| Network mocking | page.route() | Stable tests without third-party dependencies |
| HAR replay | page.routeFromHAR() | High-fidelity mocks from recorded traffic |
| Image blocking | page.route('**/*.{png,jpg}', abort) | Speed up tests by skipping images |
| CI sharding | --shard=1/4 | Split suite across parallel CI machines |
| Blob reports | --reporter=blob + merge-reports | Merge sharded results into a single report |
| Test tags | {tag: ['@smoke']} | Filter tests by category with --grep |
| Test steps | test.step('name', async () => {}) | Group actions in trace viewer and reports |
| Changed tests only | --only-changed=$GITHUB_BASE_REF | Run only test files changed since base branch |
| Native a11y checks | toHaveAccessibleName, toHaveRole | Lightweight alternative to full axe-core scans |
| Git info in reports | captureGitInfo reporter option | Link test reports to commits for CI debugging |
| Web-first assertions | expect(element).toBeVisible() | Auto-wait instead of waitForTimeout |
| Fixture composition | mergeTests() / mergeExpects() | Combine 3+ fixture modules into one test |
| Auto fixtures | {auto: true} on test.extend() | Run for every test (logging, screenshots) |
| Fixture options | {option: true} on test.extend() | Configurable via config or test.use() |
| Data-driven tests | for...of loop generating test() calls | Parameterized tests from arrays or CSV files |
| Context emulation | browser.newContext() options | locale, timezone, colorScheme, offline, isMobile |
| Two roles in one test | Concurrent browser.newContext() calls | Separate storageState per context |
Common Mistakes
| Mistake | Correct Pattern |
|---|---|
Using page.waitForTimeout() for element visibility | Use web-first assertions like expect(element).toBeVisible() which auto-wait |
| Writing raw locators directly in test files | Encapsulate all selectors in Page Object Model classes |
| Testing third-party APIs (Stripe, Auth0) directly | Mock external services with page.route() for stable, fast tests |
| Debugging CI failures with screenshots instead of traces | Configure trace: 'on-first-retry' and use Playwright Trace Viewer |
| Sharing state between tests via global variables | Use a fresh BrowserContext per test for full isolation |
| Running all tests in a single CI job | Use Playwright sharding (--shard=1/N) across parallel machines |
| Using CSS/XPath selectors for element location | Use role-based locators that survive refactors and enforce accessibility |
| Logging in via UI in every test | Use storageState with setup projects to authenticate once |
Using injectAxe/checkA11y from axe-playwright | Use AxeBuilder from @axe-core/playwright with .analyze() |
Committing storageState JSON files to git | Add playwright/.auth/ to .gitignore |
Relying on storageState for sign-out tests | Sign-out invalidates server session — sign in via UI for each sign-out test |
Assuming storageState persists sessionStorage | It only saves cookies + localStorage — use addInitScript() for sessionStorage |
| Duplicating test code for locale/currency variants | Use fixture options ({option: true}) with per-project config overrides |
Creating fixtures without mergeTests() for 3+ modules | Use mergeTests() to compose fixture files into a single test export |
Delegation
- Discover which user flows lack E2E coverage: Use
Exploreagent - Build a full Page Object Model test suite for an application: Use
Taskagent - Plan a CI sharding strategy for a large test suite: Use
Planagent
For Playwright API details, browser automation, scraping, stealth mode, screenshots/PDFs, Docker deployment, or troubleshooting Playwright errors, use the playwright skill.References
- Role-based locators, auto-waiting, chaining, filtering, and locator strategy
- Page Object Model architecture, fixtures integration, and base page patterns
- Fixtures: scoping, composition, auto fixtures, options, and data-driven tests
- Authentication with storageState, setup projects, and multi-role testing
- Network mocking, route interception, HAR replay, and WebSocket mocking
- Accessibility auditing with AxeBuilder, WCAG tags, and reusable fixtures
- Visual regression, snapshot testing, masking, tolerance thresholds, and baseline management
- CI sharding, parallelism, blob reports, and browser caching
- Test organization with tags, annotations, test.step, and project configuration