AgentSkillsCN

api-test-unit

使用 Jest 编写单元测试，支持模拟、AAA（安排—执行—断言）模式，目标覆盖率达到 80% 以上。适用于单独测试业务逻辑、处理器或服务。

SKILL.md
--- frontmatter
name: api-test-unit
description: Generate unit tests using Jest with mocking, AAA pattern (Arrange-Act-Assert), and 80%+ coverage target. Use when testing business logic, handlers, or services in isolation.
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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

code
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

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

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