Spring Boot Testing

This is a comprehensive testing guide for Spring Boot 4 that actually tells you which annotation to use when. It's built around the test pyramid and includes decision trees for choosing between @WebMvcTest, @DataJpaTest, @RestClientTest, and friends. The best part is the practical coverage: it shows you MockMvcTester (the new AssertJ-style API), Testcontainers for real database tests, and Instancio for generating test data. It also covers the Spring Boot 4 migration path from deprecated @MockBean to @MockitoBean. The complexity assessment section is refreshingly honest about when to refactor instead of writing 50 test cases for a god method. If you're moving to Spring Boot 4 or just tired of guessing which test slice to use, this gets you unstuck fast.

skills.sh installs: 215
GitHub stars: 19
last updated: Aug 21, 2026

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Install

$ npx -y skills add marcelorodrigo/agent-skills --skill spring-boot-testing --agent claude-code

Installs into .claude/skills of the current project.

Files

Spring Boot Testing

Expert guide for testing Spring Boot 4 applications with modern patterns and best practices.

Core Principles

Test Pyramid: Unit (fast) > Slice (focused) > Integration (complete)
Right Tool: Use the narrowest slice that gives you confidence
AssertJ Style: Fluent, readable assertions over verbose matchers
Modern APIs: Prefer MockMvcTester and RestTestClient over legacy alternatives

Which Test Slice?

Scenario	Annotation	Reference
Controller + HTTP semantics	`@WebMvcTest`	references/webmvctest.md
Repository + JPA queries	`@DataJpaTest`	references/datajpatest.md
REST client + external APIs	`@RestClientTest`	references/restclienttest.md
JSON (de)serialization	`@JsonTest`	See references/test-slices-overview.md
Full application	`@SpringBootTest`	See references/test-slices-overview.md