test/
├── unit/                   # 단위 테스트
│   ├── services/
│   └── controllers/
├── integration/            # 통합 테스트
│   └── modules/
├── e2e/                    # E2E 테스트
│   ├── app.e2e-spec.ts
│   └── [feature].e2e-spec.ts
└── fixtures/               # 테스트 데이터
    └── [entity].fixture.ts

# 전체 테스트
npm run test
 
# 특정 파일 테스트
npm run test -- [file-pattern]
 
# 커버리지
npm run test:cov
 
# E2E 테스트
npm run test:e2e
 
# Watch 모드
npm run test:watch

describe('UserService', () => {
  let service: UserService;
  let repository: MockType<Repository<User>>;
  beforeEach(async () => {
    const module = await Test.createTestingModule({
      providers: [
        UserService,
        { provide: getRepositoryToken(User), useFactory: repositoryMockFactory },
      ],
    }).compile();
    service = module.get<UserService>(UserService);
    repository = module.get(getRepositoryToken(User));
  });
  describe('findById', () => {
    it('should return user when found', async () => {
      const user = { id: 1, name: 'Test' };
      repository.findOne.mockReturnValue(user);
      const result = await service.findById(1);
      expect(result).toEqual(user);
    });
    it('should throw when not found', async () => {
      repository.findOne.mockReturnValue(null);
      await expect(service.findById(1)).rejects.toThrow(NotFoundException);
    });
  });
});

describe('AppController (e2e)', () => {
  let app: INestApplication;
  beforeEach(async () => {
    const moduleFixture = await Test.createTestingModule({
      imports: [AppModule],
    }).compile();
    app = moduleFixture.createNestApplication();
    await app.init();
  });
  afterEach(async () => {
    await app.close();
  });
  it('/health/live (GET)', () => {
    return request(app.getHttpServer())
      .get('/health/live')
      .expect(200)
      .expect({ status: 'ok' });
  });
});