Unit Tests

Purpose

Generate unit tests using Jest with proper mocking of dependencies, AAA pattern (Arrange-Act-Assert), and descriptive test names.

Why Jest Instead of node:test?

This repository uses Jest for ALL testing instead of Node.js's built-in node:test runner:

• Issue: nestjs/nest#14130 - NestJS @nestjs/testing is incompatible with node:test
• Impact: node:test cannot properly inject QueryBus, CommandBus, or other NestJS providers
• Solution: Jest provides full compatibility with NestJS's testing utilities and DI system

When to Use

• Testing business logic in isolation
• Testing command/query handlers
• Testing repository methods
• Testing service methods
• Unit testing utilities

What It Generates

Directory Structure

apps/api/src/modules/{feature}/__tests__/**/*.test.ts

Tests are co-located with source code but cleanly separated in __tests__/ subdirectory.

Patterns Enforced

AAA Pattern

All tests follow Arrange-Act-Assert:

• Arrange: Set up test data and mocks
• Act: Execute the function under test
• Assert: Verify expected outcomes

Descriptive Test Names

Test names should describe:

• What is being tested
• The expected outcome
• Edge cases covered

Example: should create user when valid data provided

Mocking

• Mock external dependencies
• Mock database calls
• Mock event bus
• Verify mock calls

Coverage Target

• 80%+ code coverage
• Test success and failure paths
• Test edge cases

Usage Example

/skill test-unit --name=CreateUserHandler --type=command-handler --scenarios='success,duplicate-email,database-error'

Related Files

• Test Integration - Integration tests
• Test E2E - E2E tests
• Feature CQRS - Handlers to test