spring-boot-test-patterns

# Spring Boot Testing Patterns ## Overview Comprehensive guidance for writing robust test suites for Spring Boot applications using JUnit 5, Mockito, Testcontainers, and performance-optimized slice testing patterns. ## When to Use - Writing unit tests for services or repositories with mocked dependencies - Implementing integration tests with real databases via Testcontainers - Testing REST APIs with `@WebMvcTest` or MockMvc - Configuring `@ServiceConnection` for container management in Spring Boot 3.5+ ## Quick Reference | Test Type | Annotation | Target Time | Use Case | |-----------|------------|-------------|----------| | **Unit Tests** | `@ExtendWith(MockitoExtension.class)` | < 50ms | Business logic without Spring context | | **Repository Tests** | `@DataJpaTest` | < 100ms | Database operations with minimal context | | **Controller Tests** | `@WebMvcTest` / `@WebFluxTest` | < 100ms | REST API layer testing | | **Integration Tests** | `@SpringBootTest` | < 500ms | Full application context with containers | | **Testcontainers** | `@ServiceConnection` / `@Testcontainers` | Varies | Real database/message broker containers | ## Core Concepts ### Test Architecture Philosophy 1. **Unit Tests** — Fast, isolated tests without Spring context (< 50ms) 2. **Slice Tests** — Minimal Spring context for specific layers (< 100ms) 3. **Integration Tests** — Full Spring context with real dependencies (< 500ms) ### Key Annotations **Spring Boot Test:** - `@SpringBootTest` — Full ...