MileniumTick/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-suite-structure.md, locators.md, assertions-waiting.md | | Writing component tests | component-testing.md, test-suite-structure.md | | Writing API tests | api-testing.md, test-suite-structure.md | | Writing GraphQL tests | graphql-testing.md, api-testing.md | | Writing visual regression tests | visual-regression.md, canvas-webgl.md | | Structuring test code with POM | page-object-model.md, test-suite-structure.md | | Setting up test data/fixtures | fixtures-hooks.md, test-data.md | | Handling authentication | authentication.md, authentication-flows.md | | Testing date/time features | clock-mocking.md | | Testing file upload/download | file-operations.md, file-upload-download.md | | Testing forms/validation | forms-validation.md | | Testing drag and drop | drag-drop.md | | Testing accessibility | accessibility.md | | Testing security (XSS, CSRF) | security-testing.md | | Using test annotations | annotations.md | | Using test tags | test-tags.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 |

Architecture Decisions

When to use: Choosing test patterns, deciding between approaches, planning test architecture

| Activity | Reference Files | | ---------------------------- | --------------------------------------------------------- | | POM vs fixtures decision | pom-vs-fixtures.md | | Test type selection | test-architecture.md | | Mock vs real services | when-to-mock.md | | Test suite structure | test-suite-structure.md |

Framework-Specific Testing

When to use: Testing React, Angular, Vue, or Next.js applications

| Activity | Reference Files | | ------------------------- | ----------------------------------- | | Testing React apps | react.md | | Testing Angular apps | angular.md | | Testing Vue/Nuxt apps | vue.md | | Testing Next.js apps | nextjs.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-suite-structure.md | | Improving test organization | test-suite-structure.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 | | Configuration setup | configuration.md |

Infrastructure & Configuration

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

| Activity | Reference Files | | --------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ | | Configuring Playwright project | configuration.md, projects-dependencies.md | | Setting up CI/CD pipelines | ci-cd.md, github-actions.md | | GitHub Actions setup | github-actions.md | | GitLab CI setup | gitlab.md | | Other CI providers | other-providers.md | | Docker/container setup | docker.md | | Global setup & teardown | global-setup.md | | Project dependencies | projects-dependencies.md | | Optimizing test performance | performance.md, test-suite-structure.md | | Configuring parallel execution | parallel-sharding.md, performance.md | | Isolating test data between workers | fixtures-hooks.md, performance.md | | Test coverage | test-coverage.md | | Test reporting/artifacts | reporting.md |

Advanced Patterns

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

| Activity | Reference Files | | ------------------------------------ | ------------------------------------------------------------------------------------------------------------ | | Mocking API responses | test-suite-structure.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 tags (@smoke, @fast) | test-tags.md | | Test steps for reporting | annotations.md |

Quick Decision Tree

What are you doing?
│
├─ Writing a new test?
│  ├─ E2E test → core/test-suite-structure.md, core/locators.md, core/assertions-waiting.md
│  ├─ Component test → testing-patterns/component-testing.md
│  ├─ API test → testing-patterns/api-testing.md, core/test-suite-structure.md
│  ├─ GraphQL test → testing-patterns/graphql-testing.md
│  ├─ Visual regression → testing-patterns/visual-regression.md
│  ├─ Visual/canvas test → testing-patterns/canvas-webgl.md, core/test-suite-structure.md
│  ├─ Accessibility test → testing-patterns/accessibility.md
│  ├─ Mobile/responsive test → advanced/mobile-testing.md
│  ├─ i18n/locale test → testing-patterns/i18n.md
│  ├─ Electron app test → testing-patterns/electron.md
│  ├─ Browser extension test → testing-patterns/browser-extensions.md
│  ├─ Multi-user test → advanced/multi-user.md
│  ├─ Form validation test → testing-patterns/forms-validation.md
│  └─ Drag and drop test → testing-patterns/drag-drop.md
│
├─ Testing specific features?
│  ├─ File upload/download → testing-patterns/file-operations.md, testing-patterns/file-upload-download.md
│  ├─ Date/time dependent → advanced/clock-mocking.md
│  ├─ WebSocket/real-time → browser-apis/websockets.md
│  ├─ Geolocation/permissions → browser-apis/browser-apis.md
│  ├─ OAuth/SSO mocking → advanced/third-party.md, advanced/multi-context.md
│  ├─ Payments/email/SMS → advanced/third-party.md
│  ├─ iFrames → browser-apis/iframes.md
│  ├─ Canvas/WebGL/charts → testing-patterns/canvas-webgl.md
│  ├─ Service workers/PWA → browser-apis/service-workers.md
│  ├─ i18n/localization → testing-patterns/i18n.md
│  ├─ Security (XSS, CSRF) → testing-patterns/security-testing.md
│  └─ Performance/Web Vitals → testing-patterns/performance-testing.md
│
├─ Architecture decisions?
│  ├─ POM vs fixtures → architecture/pom-vs-fixtures.md
│  ├─ Test type selection → architecture/test-architecture.md
│  ├─ Mock vs real services → architecture/when-to-mock.md
│  └─ Test suite structure → core/test-suite-structure.md
│
├─ Framework-specific testing?
│  ├─ React app → frameworks/react.md
│  ├─ Angular app → frameworks/angular.md
│  ├─ Vue/Nuxt app → frameworks/vue.md
│  └─ Next.js app → frameworks/nextjs.md
│
├─ Authentication testing?
│  ├─ Basic auth patterns → advanced/authentication.md
│  └─ Complex flows (MFA, reset) → advanced/authentication-flows.md
│
├─ Test is failing/flaky?
│  ├─ Flaky test investigation → debugging/flaky-tests.md
│  ├─ Element not found → core/locators.md, debugging/debugging.md
│  ├─ Timeout issues → core/assertions-waiting.md, debugging/debugging.md
│  ├─ Race conditions → debugging/flaky-tests.md, debugging/debugging.md
│  ├─ Flaky only with multiple workers → debugging/flaky-tests.md, infrastructure-ci-cd/performance.md
│  ├─ State leak / isolation → debugging/flaky-tests.md, core/fixtures-hooks.md
│  ├─ Console/JS errors → debugging/console-errors.md, debugging/debugging.md
│  └─ General debugging → debugging/debugging.md
│
├─ Testing error scenarios?
│  ├─ Network failures → debugging/error-testing.md, advanced/network-advanced.md
│  ├─ Offline (unexpected) → debugging/error-testing.md
│  ├─ Offline-first/PWA → browser-apis/service-workers.md
│  ├─ Error boundaries → debugging/error-testing.md
│  └─ Form validation → testing-patterns/forms-validation.md, debugging/error-testing.md
│
├─ Refactoring existing code?
│  ├─ Implementing POM → core/page-object-model.md
│  ├─ Improving selectors → core/locators.md
│  ├─ Extracting fixtures → core/fixtures-hooks.md
│  ├─ Creating data factories → core/test-data.md
│  └─ Configuration setup → core/configuration.md
│
├─ Setting up infrastructure?
│  ├─ CI/CD → infrastructure-ci-cd/ci-cd.md
│  ├─ GitHub Actions → infrastructure-ci-cd/github-actions.md
│  ├─ GitLab CI → infrastructure-ci-cd/gitlab.md
│  ├─ Other CI providers → infrastructure-ci-cd/other-providers.md
│  ├─ Docker/containers → infrastructure-ci-cd/docker.md
│  ├─ Sharding/parallel → infrastructure-ci-cd/parallel-sharding.md
│  ├─ Reporting/artifacts → infrastructure-ci-cd/reporting.md
│  ├─ Global setup/teardown → core/global-setup.md
│  ├─ Project dependencies → core/projects-dependencies.md
│  ├─ Test performance → infrastructure-ci-cd/performance.md
│  ├─ Test coverage → infrastructure-ci-cd/test-coverage.md
│  └─ Project config → core/configuration.md, core/projects-dependencies.md
│
├─ Organizing tests?
│  ├─ Skip/fixme/slow tests → core/annotations.md
│  ├─ Test tags (@smoke, @fast) → core/test-tags.md
│  ├─ Filtering tests (--grep) → core/test-tags.md
│  ├─ Test steps → core/annotations.md
│  └─ Conditional execution → core/annotations.md
│
└─ Running subset of tests?
   ├─ By tag (@smoke, @critical) → core/test-tags.md
   ├─ Exclude slow/flaky tests → core/test-tags.md
   ├─ PR vs nightly tests → core/test-tags.md, infrastructure-ci-cd/ci-cd.md
   └─ Project-specific filtering → core/test-tags.md, core/configuration.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