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

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

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('[email protected]');

// 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

1. Repository shape:

• Confirm working directory and expected app root exist.
• Verify spec paths before execution (rg --files tests/e2e | rg <target>).

2. Port/process hygiene:

• Check and clear stale dev server port before run (example: lsof -i :3001).
• Avoid parallel local servers colliding with Playwright webServer.

3. Command validity:

• Validate CLI flags for current tool versions before batch runs.
• Prefer exact spec paths or --grep over broad globs during triage.

4. 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)

1. Reproduce one failing test with --workers=1.
2. Capture trace/video/screenshot for that single failure.
3. Fix determinism root cause.
4. Re-run targeted suite.
5. 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

Templates

Related Skills

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.