qa-testing-playwright

SKILL.md

QA Testing (Playwright)

High-signal, cost-aware E2E testing for web applications.

Core docs:

https://playwright.dev/docs/best-practices

https://playwright.dev/docs/locators

https://playwright.dev/docs/test-retries

https://playwright.dev/docs/trace-viewer

https://playwright.dev/docs/test-sharding

https://playwright.dev/docs/ci

Defaults (2026)

Keep E2E thin: protect critical user journeys only; push coverage down (unit/integration/contract).

Locator priority: getByRole → getByLabel/getByText → getByTestId (fallback).

Waiting: rely on Playwright auto-wait + web-first assertions; no sleeps/time-based waits.

Isolation: tests must run alone, in parallel, and in any order; eliminate shared mutable state.

Flake posture: retries are a debugging tool; treat rerun-pass as a failure signal and fix root cause.

CI posture: smoke gate on PRs; shard/parallelize regression on schedule; always keep artifacts (trace/video/screenshot).

Quick Start

Command
Purpose

npm init playwright@latest
Initialize Playwright

npx playwright test
Run all tests

npx playwright test --grep @smoke
Run smoke tests

npx playwright test --project=chromium
Run a single project

npx playwright test --ui
Debug with UI mode

npx playwright test --debug
Step through a test

npx playwright show-trace trace.zip
Inspect trace artifacts

npx playwright show-report
Inspect HTML report

When to Use

E2E tests for web applications

Test user authentication flows

Verify form submissions

Test responsive designs

Automate browser interactions

Set up Playwright in CI/CD

When NOT to Use

Scenario
Use Instead

Unit testing
Jest, Vitest, pytest

API contracts
qa-api-testing-contracts

Load testing
k6, Locust, Artillery

Mobile native
Appium

Authoring Rules

Locator Strategy

// 1. Role locators (preferred)
await page.getByRole('button', { name: 'Sign in' }).click();

// 2. Label/text locators
await page.getByLabel('Email').fill('user@example.com');

// 3. Test IDs (fallback)
await page.getByTestId('user-avatar').click();

Flake Control

Avoid sleeps; use Playwright auto-wait

Use retries as signal, not a crutch

Capture trace/screenshot/video on failure

Prefer user-like interactions; avoid force: true

Workflow

Write the smallest test that proves the user outcome (intent + oracle).

Stabilize locators and assertions before adding more steps.

Make state explicit: seed per test/worker, clean up deterministically, mock third-party boundaries.

In CI: shard/parallelize, capture artifacts, and fail fast on rerun-pass flakes.

Debugging Checklist

If something is flaky:

Open trace first; identify whether it is selector ambiguity, missing wait, or state leakage.

Replace brittle selectors with semantic locators; replace sleeps with expect(...) or a targeted wait.

Reduce global timeouts; add scoped timeouts only when the product truly needs it.

If it only fails in CI, look for concurrency, cold-start, CPU starvation, and environment differences.

Do / Avoid

Make tests independent and deterministic

Use network mocking for third-party deps

Run smoke E2E on PRs; full regression on schedule

"Test everything E2E" as default

Weakening assertions to "fix" flakes

Auto-healing that weakens assertions

Execution Preflight (High ROI)

Run this preflight before expensive E2E runs to prevent avoidable failures.

Preflight Checklist

Repository shape:

Confirm working directory and expected app root exist.

Verify spec paths before execution (rg --files tests/e2e | rg <target>).

Port/process hygiene:

Check and clear stale dev server port before run (example: lsof -i :3001).

Avoid parallel local servers colliding with Playwright webServer.

Command validity:

Validate CLI flags for current tool versions before batch runs.

Prefer exact spec paths or --grep over broad globs during triage.

Artifact expectations:

Confirm result artifact paths exist before reading (test -f <error-context.md>).

If artifact path missing, inspect latest test-results index first.

Mandatory Sandbox/Port Decisions

Before running Playwright in constrained environments (sandboxed terminals, CI containers, shared dev hosts), decide and document:

Bind host/port: confirm whether app server must use 127.0.0.1 or 0.0.0.0, and verify selected port is free.

Escalation path: if bind attempts fail with EPERM/EACCES, escalate immediately instead of retry loops.

Long-flow timeout budget: set explicit per-test timeout for API-heavy flows (generation/checkout/report) instead of inflating global timeout.

Build lock hygiene: clear stale .next/lock and terminate stale build/dev PIDs before rerun.

Triage Sequence (Fastest Signal)

Reproduce one failing test with --workers=1.

Capture trace/video/screenshot for that single failure.

Fix determinism root cause.

Re-run targeted suite.

Only then run broad regression.

Failure Patterns to Treat as Environment, Not Product Bugs

EADDRINUSE on Playwright web server port

Missing spec/result paths from stale assumptions

Shell glob expansion failures for bracketed route segments

Resources

Resource
Purpose

references/playwright-mcp.md
MCP & AI testing

references/playwright-patterns.md
Advanced patterns

references/playwright-ci.md
CI configurations

references/playwright-authentication.md
Auth patterns and session management

references/visual-regression-testing.md
Visual regression strategies

references/api-testing-playwright.md
API testing with APIRequestContext

references/playwright-preflight-sandbox.md
Sandbox/port preflight and escalation decisions

data/sources.json
Documentation links

Templates

Template
Purpose

assets/template-playwright-e2e-review-checklist.md
E2E review checklist

assets/template-playwright-fail-on-flaky-reporter.js
Fail CI on rerun-pass flakes

assets/template-playwright-preflight-checklist.md
Preflight checklist for port/sandbox/timeouts

Related Skills

Skill
Purpose

qa-testing-strategy
Overall test strategy

software-frontend
Frontend development

ops-devops-platform
CI/CD integration

Fact-Checking

Use web search/web fetch to verify current external facts, versions, pricing, deadlines, regulations, or platform behavior before final answers.

Prefer primary sources; report source links and dates for volatile information.

If web access is unavailable, state the limitation and mark guidance as unverified.

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