Cursor-rules-java 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 @MockitoBean for controllers, @JsonTest for JSON serialization, parameterized tests with @CsvSource/@MethodSource, test profiles, and @TestConfiguration. For framework-agnostic Java use @131-java-testing-unit-testing. For integration tests use @322-frameworks-spring-boot-testing-integration-tests. Part of the skills-for-java project

install

source · Clone the upstream repo

git clone https://github.com/jabrena/cursor-rules-java

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/jabrena/cursor-rules-java "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/321-frameworks-spring-boot-testing-unit-tests" ~/.claude/skills/jabrena-cursor-rules-java-321-frameworks-spring-boot-testing-unit-tests && rm -rf "$T"

manifest: skills/321-frameworks-spring-boot-testing-unit-tests/SKILL.md

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, @MockitoBean for controllers (Spring Boot 4.0.x — @MockBean removed)
@JsonTest for JSON serialization with correct JSON value assertions (extractingJsonPathStringValue, etc.)
Parameterized tests: @ParameterizedTest with @CsvSource or @MethodSource over copy-pasted methods
Java records for domain objects in tests
@TestConfiguration, @ActiveProfiles, @Primary fixed-clock beans for deterministic test setup
Modern mocking API: @MockitoBean / @MockitoSpyBean; @MockBean/@SpyBean are deprecated/removed in Boot 4.0.x

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.