Unit Testing Skill

When to Use

• Writing unit tests for frontend or backend
• Reviewing test coverage and isolation
• Refactoring test structure

Critical Patterns

Frontend

• Use RTL for user-centric tests
• Mock dependencies and hooks
• Test UI logic in isolation

Backend

• Use Jest for logic isolation
• Mock I/O and external services
• Test pure functions and modules

Decision Tree

• UI or logic? → Use RTL or Jest
• Need mocks? → Use jest.mock or manual mocks
• Async code? → Use async/await in tests

Edge Cases

• Flaky async tests
• Mocking native modules
• Coverage gaps