Vue Testing Best Practices

This is a troubleshooting-oriented testing guide that maps specific Vue 3 testing problems to solutions. It covers the practical stuff you'll actually hit: Pinia injection errors, flaky async tests, composables that won't test because of lifecycle hooks, and teleported content that disappears from your queries. The structure is problem-first rather than theoretical, which is refreshing. It assumes you're using Vitest and Vue Test Utils, pushes you toward black-box component testing over implementation details, and includes Playwright guidance for E2E. If you're already testing Vue apps, you've probably searched for half these issues. If you're just starting, this gives you the modern stack without wading through outdated Vue 2 advice.