131 Java Testing Unit Testing
Use when you need to review, improve, or write Java unit tests — including migrating from JUnit 4 to JUnit 5, adopting AssertJ for fluent assertions, structuring tests with Given-When-Then, ensuring test independence, applying parameterized tests, mocking dependencies with Mockito, verifying boundary conditions (RIGHT-BICEP, CORRECT, A-TRIP), leveraging JSpecify null-safety annotations, or elimin…
Install
$ agentstack add skill-jabrena-cursor-rules-java-131-java-testing-unit-testing ✓ scanned · ✓ verified, works with Claude Code, Cursor, and more.
Security review
✓ PassedNo issues found. Passed automated security review. · v0.1.0 How review works →
- ✓ Prompt-injection patterns
- ✓ Secret / credential exfiltration
- ✓ Dangerous shell & filesystem operations
- ✓ Untrusted network calls
- ✓ Known-malicious package signatures
What it can access
- ✓ Network access No
- ✓ Filesystem access No
- ✓ Shell / process execution No
- ✓ Environment & secrets No
- ✓ Dynamic code execution No
From automated source analysis of v0.1.0. “Used” means the capability is present in the source — more access means more to trust, not that it’s unsafe.
Verified badge
Passed review? Show it. Paste this badge into your README, it links to the public security report.
Links to your public security report.[](https://agentstack.voostack.com/security/report/skill-jabrena-cursor-rules-java-131-java-testing-unit-testing) Reliability & compatibility
Declared compatibility
Compatibility is declared by the source manifest. End-to-end runtime verification is coming, see below.
We're building live execution health for every listing: tool-call success rate, median latency, uptime, and last-checked timestamps, measured, not self-reported. It isn't live yet, so we don't show numbers we can't stand behind.
How agent discovery & health will work →About
Java Unit testing guidelines
Review and improve Java unit tests using modern JUnit 5, AssertJ, and Mockito best practices.
What is covered in this Skill?
- JUnit 5 annotations:
@Test,@BeforeEach,@AfterEach,@DisplayName,@Nested,@ParameterizedTest - AssertJ fluent assertions:
assertThat,assertThatThrownBy - Given-When-Then test structure, descriptive test naming, single-responsibility tests
- Test independence and isolated state
- Parameterized tests:
@ValueSource/@CsvSource/@MethodSource - Mockito dependency mocking:
@Mock,@InjectMocks,MockitoExtension - Code coverage guidance (JaCoCo), package-private test visibility
- Testing anti-patterns: reflection, shared state, hard-coded values, testing implementation details
- Error handling:
assertThatThrownBy, exception messages - JSpecify null-safety:
@NullMarked,@Nullable - RIGHT-BICEP coverage principles, A-TRIP test quality, CORRECT boundary condition verification
Scope: The reference is organized by examples (good/bad code patterns) for each core area. Apply recommendations based on applicable examples.
Constraints
Before applying any unit test changes, ensure the project compiles. If compilation fails, stop immediately — do not proceed until resolved. After applying improvements, run full verification.
- MANDATORY: Run
./mvnw compileormvn compilebefore applying any change - SAFETY: If compilation fails, stop immediately and do not proceed — compilation failure is a blocking condition
- VERIFY: Run
./mvnw clean verifyormvn clean verifyafter applying improvements - BEFORE APPLYING: Read the reference for detailed examples, good/bad patterns, and constraints
When to use this skill
- Review Java code for unit tests
- Apply best practices for unit tests in Java code
Workflow
- Compile project before unit-test changes
Run ./mvnw compile or mvn compile and stop immediately if compilation fails.
- Read unit-testing reference and evaluate coverage
Read references/131-java-testing-unit-testing.md and identify modernization and quality gaps in current tests.
- Apply unit-testing best practices
Implement or refactor tests using JUnit 5, AssertJ, Mockito, parameterization, and stronger boundary checks.
- Verify with full build
Run ./mvnw clean verify or mvn clean verify after applying improvements.
Reference
For detailed guidance, examples, and constraints, see [references/131-java-testing-unit-testing.md](references/131-java-testing-unit-testing.md).
Source & license
This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.
- Author: jabrena
- Source: jabrena/cursor-rules-java
- License: Apache-2.0
- Homepage: https://jabrena.github.io/cursor-rules-java/
Install and usage instructions live in the source repository linked above.
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Versions
- v0.1.0 Imported from the upstream source.