# 321 Frameworks Spring Boot Testing Unit Tests

> Use when you need to write unit tests for Spring Boot applications — including pure unit tests with @ExtendWith(MockitoExtension.class) for @Service/@Component, slice tests with @WebMvcTest and @MockBean for controllers, @JsonTest for JSON serialization. For framework-agnostic Java use @131-java-testing-unit-testing. Part of the skills-for-java project

- Skill: `jabrena/321-frameworks-spring-boot-testing-unit-tests` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add jabrena/321-frameworks-spring-boot-testing-unit-tests`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jabrena/321-frameworks-spring-boot-testing-unit-tests/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- License: Apache-2.0
- Author: jabrena (https://skillmd.com/u/jabrena)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/jabrena/321-frameworks-spring-boot-testing-unit-tests

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# Spring Boot Unit Testing with Mockito

Apply Spring Boot unit testing guidelines with Mockito.

**What is covered in this Skill?**

- Pure unit tests: @ExtendWith(MockitoExtension.class), @Mock, @InjectMocks for @Service/@Component (no Spring context)
- Slice tests: @WebMvcTest, @MockBean for controllers
- @JsonTest for JSON serialization
- @TestConfiguration, @ActiveProfiles for test setup

**Scope:** Apply recommendations based on the reference rules and good/bad code examples. For integration tests use @322-frameworks-spring-boot-testing-integration-tests.

## Constraints

Before applying any test changes, ensure the project compiles. If compilation fails, stop immediately. After applying improvements, run full verification.

- **MANDATORY**: Run `./mvnw compile` or `mvn compile` before applying any change
- **SAFETY**: If compilation fails, stop immediately
- **VERIFY**: Run `./mvnw clean verify` or `mvn clean verify` after applying improvements
- **BEFORE APPLYING**: Read the reference for detailed rules and good/bad patterns

## When to use this skill

- Review Java code for Spring Boot unit tests
- Apply best practices for Spring Boot unit tests in Java code

## Reference

For detailed guidance, examples, and constraints, see [references/321-frameworks-spring-boot-testing-unit-tests.md](references/321-frameworks-spring-boot-testing-unit-tests.md).