Testing Guide

This skill provides a pragmatic testing strategy for backend services.

1. Principles

• •Prefer fast unit tests for business logic (service layer).
• •Use integration tests for routes and repositories when needed.
• •Keep tests deterministic (fixed inputs, stable fixtures, clear assertions).

2. What to test by layer

Routes/controllers

• •HTTP status codes and response shape
• •Input validation behavior (invalid input → 400)
• •Auth/permission behavior (missing/invalid auth → 401/403)

Services

• •Business rules and edge cases
• •Idempotency and invariants
• •Error conditions (typed domain errors)

Repositories

• •Query correctness and filtering/pagination behavior
• •Transactional behavior (multi-write operations)

3. Common anti-patterns

• •Tests that depend on real clocks (use time injection or fakes)
• •Tests that require external services without a stable harness
• •"Golden" snapshots for dynamic responses without normalization

4. Checklist (before merging changes)

• • Service logic covered by unit tests
• • At least one integration test covers the route(s) you changed
• • Failure paths are tested (validation/auth/not found)
• • Monitoring/error capture behavior is testable where possible

Related Skills

• •architecture-overview
• •services-and-repositories