spring-boot-testing-strategylisted

# Testing Strategy ## Testing Pyramid ```text /\ / \ / E2E\ 10% — full API, happy path + main error cases /------\ / Integ \ 20% — components with real dependencies (DB, HTTP) /----------\ / Unit \ 70% — isolated, mocked dependencies, fast /______________\ ``` Unit tests are the foundation. They are fast, deterministic, and cheap to run. Integration tests validate that components work together. E2E tests validate that the system works end to end — keep them minimal. If you find yourself writing more integration tests than unit tests, the code under test has too many responsibilities bundled together. ## Test Naming Convention Format: `should [expected behavior] when [condition]` ```kotlin @Test fun `should return user when found by id`() { ... } @Test fun `should return 404 when user does not exist`() { ... } @Test fun `should throw ConflictException when email already exists`() { ... } @Test fun `should not return deleted users in list`() { ... } ``` Group related tests with `@Nested`: ```kotlin @ExtendWith(MockKExtension::class) class UserServiceTest { @Nested inner class GetById { @Test fun `should return user when found`() { ... } @Test fun `should return NotFound when user does not exist`() { ... } } @Nested inner class Create { @Test fun `should create and return user when email is unique`() { ... } @Test fun `should throw C