Software Testing

Testing Decision Tree

Need to write tests?
    ↓
    Legacy/undocumented code needing refactoring?
    ├─ YES → Use characterization-testing skill
    └─ NO  → Continue
              ↓
              What type of testing guidance needed?
              │
              ├─ Unit testing principles?
              │  └─→ See references/unit-testing.md
              │
              ├─ Using Jest?
              │  └─→ See references/jest-testing.md
              │
              ├─ Using Vitest?
              │  └─→ See references/vitest-testing.md
              │
              ├─ Testing React components?
              │  └─→ See references/react-testing.md
              │
              └─ Testing Node.js code?
                 └─→ See references/node-testing.md

Core Testing Principles

Apply these principles across all testing approaches:

Keep Test Scope Small

Run only the tests you need. Prefer narrow scope over full test suites.

Good:

npm test src/auth/login.test.js
npm test -- --testNamePattern="login validation"

Avoid:

npm test  # Running entire suite unnecessarily

Use Specific Assertion Values

Write assertions with actual expected values, not generic placeholders.

Good:

expect(user.name).toBe('Alice')
expect(getUserById).toHaveBeenCalledWith('user-123')

Avoid:

expect(users.length).toBe(2)
expect(getUserById).toHaveBeenCalledWith(expect.any(String))

Check Repo-Specific Skills First

Before running tests:

1. Check what Project skills are available for testing guidance
2. Check test configuration files
3. Ask user if uncertain

Reference Guide

• references/unit-testing.md - Unit testing principles (SRP, isolation, mocking, what to test)
• references/jest-testing.md - Jest commands, matchers, and patterns
• references/vitest-testing.md - Vitest commands and differences from Jest
• references/react-testing.md - React Testing Library query priorities and patterns
• references/node-testing.md - Node.js-specific testing (async, streams, file system)