Playwright best practices

Playwright Best Practices

This skill provides comprehensive guidance for all aspects of Playwright test development, from writing new tests to debugging and maintaining existing test suites.

Activity-Based Reference Guide

Consult these references based on what you're doing:

Writing New Tests

When to use: Creating new test files, writing test cases, implementing test scenarios

Activity	Reference Files
Writing E2E tests	test-organization.md, locators.md, assertions-waiting.md
Writing component tests	component-testing.md, test-organization.md
Writing API tests	test-organization.md, assertions-waiting.md
Writing visual regression tests	test-organization.md, canvas-webgl.md
Structuring test code with POM	page-object-model.md, test-organization.md
Setting up test data/fixtures	fixtures-hooks.md, test-data.md
Handling authentication	fixtures-hooks.md, third-party.md
Testing date/time features	clock-mocking.md
Testing file upload/download	file-operations.md
Testing accessibility	accessibility.md
Testing security (XSS, CSRF)	security-testing.md
Using test annotations	annotations.md
Testing iframes	iframes.md
Testing canvas/WebGL	canvas-webgl.md
Internationalization (i18n)	i18n.md
Testing Electron apps	electron.md
Testing browser extensions	browser-extensions.md

Mobile & Responsive Testing

When to use: Testing mobile devices, touch interactions, responsive layouts

Activity	Reference Files
Device emulation	mobile-testing.md
Touch gestures (swipe, tap)	mobile-testing.md
Viewport/breakpoint testing	mobile-testing.md
Mobile-specific UI	mobile-testing.md, locators.md

Real-Time & Browser APIs

When to use: Testing WebSockets, geolocation, permissions, multi-tab flows

Activity	Reference Files
WebSocket/real-time testing	websockets.md
Geolocation mocking	browser-apis.md
Permission handling	browser-apis.md
Clipboard testing	browser-apis.md
Camera/microphone mocking	browser-apis.md
Multi-tab/popup flows	multi-context.md
OAuth popup handling	third-party.md, multi-context.md

Debugging & Troubleshooting

When to use: Test failures, element not found, timeouts, unexpected behavior

Activity	Reference Files
Debugging test failures	debugging.md, assertions-waiting.md
Fixing flaky tests	flaky-tests.md, debugging.md, assertions-waiting.md
Debugging flaky parallel runs	flaky-tests.md, performance.md, fixtures-hooks.md
Ensuring test isolation / avoiding state leak	flaky-tests.md, fixtures-hooks.md, performance.md
Fixing selector issues	locators.md, debugging.md
Investigating timeout issues	assertions-waiting.md, debugging.md
Using trace viewer	debugging.md
Debugging race conditions	flaky-tests.md, debugging.md, assertions-waiting.md
Debugging console/JS errors	console-errors.md, debugging.md

Error & Edge Case Testing

When to use: Testing error states, offline mode, network failures, validation

Activity	Reference Files
Error boundary testing	error-testing.md
Network failure simulation	error-testing.md, network-advanced.md
Offline mode testing	error-testing.md, service-workers.md
Service worker testing	service-workers.md
Loading state testing	error-testing.md
Form validation testing	error-testing.md

Multi-User & Collaboration Testing

When to use: Testing features involving multiple users, roles, or real-time collaboration

Activity	Reference Files
Multiple users in one test	multi-user.md
Real-time collaboration	multi-user.md, websockets.md
Role-based access testing	multi-user.md
Concurrent action testing	multi-user.md

Refactoring & Maintenance

When to use: Improving existing tests, code review, reducing duplication

Activity	Reference Files
Refactoring to Page Object Model	page-object-model.md, test-organization.md
Improving test organization	test-organization.md, page-object-model.md
Extracting common setup/teardown	fixtures-hooks.md
Replacing brittle selectors	locators.md
Removing explicit waits	assertions-waiting.md
Creating test data factories	test-data.md

Infrastructure & Configuration

When to use: Setting up projects, configuring CI/CD, optimizing performance

Activity	Reference Files
Configuring Playwright project	test-organization.md, projects-dependencies.md
Setting up CI/CD pipelines	ci-cd.md, performance.md
Global setup & teardown	global-setup.md
Project dependencies	projects-dependencies.md
Optimizing test performance	performance.md, test-organization.md
Configuring parallel execution	performance.md
Isolating test data between workers	fixtures-hooks.md, performance.md
Test coverage	test-coverage.md

Advanced Patterns

When to use: Complex scenarios, API mocking, network interception

Activity	Reference Files
Mocking API responses	test-organization.md, network-advanced.md
Network interception	network-advanced.md, assertions-waiting.md
GraphQL mocking	network-advanced.md
HAR recording/playback	network-advanced.md
Custom fixtures	fixtures-hooks.md
Advanced waiting strategies	assertions-waiting.md
OAuth/SSO mocking	third-party.md, multi-context.md
Payment gateway mocking	third-party.md
Email/SMS verification mocking	third-party.md
Failing on console errors	console-errors.md
Security testing (XSS, CSRF)	security-testing.md
Performance budgets & Web Vitals	performance-testing.md
Lighthouse integration	performance-testing.md
Test annotations (skip, fixme)	annotations.md
Test steps for reporting	annotations.md

Quick Decision Tree

What are you doing?
│
├─ Writing a new test?
│  ├─ E2E test → test-organization.md, locators.md, assertions-waiting.md
│  ├─ Component test → component-testing.md
│  ├─ API test → test-organization.md, assertions-waiting.md
│  ├─ Visual/canvas test → canvas-webgl.md, test-organization.md
│  ├─ Accessibility test → accessibility.md
│  ├─ Mobile/responsive test → mobile-testing.md
│  ├─ i18n/locale test → i18n.md
│  ├─ Electron app test → electron.md
│  ├─ Browser extension test → browser-extensions.md
│  └─ Multi-user test → multi-user.md
│
├─ Testing specific features?
│  ├─ File upload/download → file-operations.md
│  ├─ Date/time dependent → clock-mocking.md
│  ├─ WebSocket/real-time → websockets.md
│  ├─ Geolocation/permissions → browser-apis.md
│  ├─ OAuth/SSO mocking → third-party.md, multi-context.md
│  ├─ Payments/email/SMS → third-party.md
│  ├─ iFrames → iframes.md
│  ├─ Canvas/WebGL/charts → canvas-webgl.md
│  ├─ Service workers/PWA → service-workers.md
│  ├─ i18n/localization → i18n.md
│  ├─ Security (XSS, CSRF) → security-testing.md
│  └─ Performance/Web Vitals → performance-testing.md
│
├─ Test is failing/flaky?
│  ├─ Flaky test investigation → flaky-tests.md
│  ├─ Element not found → locators.md, debugging.md
│  ├─ Timeout issues → assertions-waiting.md, debugging.md
│  ├─ Race conditions → flaky-tests.md, debugging.md
│  ├─ Flaky only with multiple workers → flaky-tests.md, performance.md
│  ├─ State leak / isolation → flaky-tests.md, fixtures-hooks.md
│  ├─ Console/JS errors → console-errors.md, debugging.md
│  └─ General debugging → debugging.md
│
├─ Testing error scenarios?
│  ├─ Network failures → error-testing.md, network-advanced.md
│  ├─ Offline (unexpected) → error-testing.md
│  ├─ Offline-first/PWA → service-workers.md
│  ├─ Error boundaries → error-testing.md
│  └─ Form validation → error-testing.md
│
├─ Refactoring existing code?
│  ├─ Implementing POM → page-object-model.md
│  ├─ Improving selectors → locators.md
│  ├─ Extracting fixtures → fixtures-hooks.md
│  └─ Creating data factories → test-data.md
│
├─ Setting up infrastructure?
│  ├─ CI/CD → ci-cd.md
│  ├─ Global setup/teardown → global-setup.md
│  ├─ Project dependencies → projects-dependencies.md
│  ├─ Test performance → performance.md
│  ├─ Test coverage → test-coverage.md
│  └─ Project config → test-organization.md, projects-dependencies.md
│
└─ Organizing tests?
   ├─ Skip/fixme/slow tests → annotations.md
   ├─ Test steps → annotations.md
   └─ Conditional execution → annotations.md

Test Validation Loop

After writing or modifying tests:

1. Run tests: npx playwright test --reporter=list
2. If tests fail:
   • Review error output and trace (npx playwright show-trace)
   • Fix locators, waits, or assertions
   • Re-run tests
3. Only proceed when all tests pass
4. Run multiple times for critical tests: npx playwright test --repeat-each=5