references/
├── common/              # Core testing fundamentals
│   ├── knowledge.md     # Testing philosophy and test pyramid
│   ├── rules.md         # Mandatory testing rules (AAA, naming, coverage)
│   ├── assertions.md    # Assertion patterns and matchers
│   ├── examples.md      # Comprehensive examples by category
│   ├── detect-open-handles.md   # Open handle detection and cleanup
│   └── performance-optimization.md  # Jest runtime optimization
│
├── nestjs/              # NestJS component testing
│   ├── services.md      # Service/usecase testing patterns
│   ├── controllers.md   # Controller testing patterns
│   ├── guards.md        # Guard testing patterns
│   ├── interceptors.md  # Interceptor testing patterns
│   └── pipes-filters.md # Pipe and filter testing
│
├── mocking/             # Mock patterns and strategies
│   ├── deep-mocked.md   # @golevelup/ts-jest patterns
│   ├── jest-native.md   # Jest.fn, spyOn, mock patterns
│   └── factories.md     # Test data factory patterns
│
├── repository/          # Repository testing
│   ├── mongodb.md       # mongodb-memory-server patterns
│   └── postgres.md      # pg-mem patterns
│
├── kafka/               # NestJS Kafka microservices testing
│   └── kafka.md         # ClientKafka, @MessagePattern, @EventPattern handlers
│
└── redis/               # Redis cache testing
    └── redis.md         # Cache operations, health checks, graceful degradation

undefined

**Temp Files** (with `${UT_SESSION}` unique per agent):
- `/tmp/ut-${UT_SESSION}-output.log` - Full test output
- `/tmp/ut-${UT_SESSION}-failures.md` - Tracking file for one-by-one fixing
- `/tmp/ut-${UT_SESSION}-debug.log` - Debug runs
- `/tmp/ut-${UT_SESSION}-verify.log` - Verification runs
- `/tmp/ut-${UT_SESSION}-coverage.log` - Coverage output

it('should return user when found', async () => {
  // Arrange
  const userId = 'user-123';
  mockRepository.findById.mockResolvedValue({
    id: userId,
    email: 'test@example.com',
    name: 'Test User',
  });

  // Act
  const result = await target.getUser(userId);

  // Assert
  expect(result).toEqual({
    id: userId,
    email: 'test@example.com',
    name: 'Test User',
  });
  expect(mockRepository.findById).toHaveBeenCalledWith(userId);
});

let target: UserService;
let mockRepository: DeepMocked<UserRepository>;

import { createMock, DeepMocked } from '@golevelup/ts-jest';

let mockService: DeepMocked<UserService>;

beforeEach(() => {
  mockService = createMock<UserService>();
});

// WRONG
expect(result).toBeDefined();
expect(result.id).toBeDefined();

// CORRECT
expect(result).toEqual({
  id: 'user-123',
  email: 'test@example.com',
  name: 'Test User',
});

// Unit Test: Mock repository
{ provide: UserRepository, useValue: mockRepository }

// Repository Test: Use in-memory database
const mongoServer = await createMongoMemoryServer();

import { Test, TestingModule } from '@nestjs/testing';
import { createMock, DeepMocked } from '@golevelup/ts-jest';
import { MockLoggerService } from 'src/shared/logger/services/mock-logger.service';

describe('UserService', () => {
  let target: UserService;
  let mockRepository: DeepMocked<UserRepository>;

  beforeEach(async () => {
    // Arrange: Create mocks
    mockRepository = createMock<UserRepository>();

    const module: TestingModule = await Test.createTestingModule({
      providers: [
        UserService,
        { provide: UserRepository, useValue: mockRepository },
      ],
    })
      .setLogger(new MockLoggerService())
      .compile();

    target = module.get<UserService>(UserService);
  });

  afterEach(() => {
    jest.clearAllMocks();
  });

  describe('getUser', () => {
    it('should return user when found', async () => {
      // Arrange
      mockRepository.findById.mockResolvedValue({
        id: 'user-123',
        email: 'test@example.com',
      });

      // Act
      const result = await target.getUser('user-123');

      // Assert
      expect(result).toEqual({ id: 'user-123', email: 'test@example.com' });
    });

    it('should throw NotFoundException when user not found', async () => {
      // Arrange
      mockRepository.findById.mockResolvedValue(null);

      // Act & Assert
      await expect(target.getUser('invalid')).rejects.toThrow(NotFoundException);
    });
  });
});

describe('ClassName', () => {
  describe('methodName', () => {
    it('should [expected behavior] when [condition]', () => {});
  });
});