Web Testing Skill

Version: 1.0 Stack: React Testing Library + Jest + Prisma

The wrong testing strategy wastes more time than no tests at all. Tests that test implementation break every time you refactor. Tests that share state flake randomly. Tests without error cases give false confidence — your suite is green but your app crashes on the first unexpected input. You write tests, they break for the wrong reasons, and the team stops trusting them.

Behavior-focused tests survive refactoring. Isolated tests never flake. The testing pyramid keeps the suite fast enough that people actually run it. These patterns produce tests you can trust.

Core Principles

1. Test Behavior, Not Implementation — Test what users see and do, not internal details.
2. Pyramid Structure — Many unit tests, fewer integration, minimal E2E.
3. Fast Feedback — Tests should run in seconds, not minutes.
4. Deterministic — Same input = same output. No flaky tests.
5. Isolated — Tests don't depend on each other or external state.