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 eliminating testing anti-patterns such as reflection-based tests or shared mutable state. This should trig…
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 eliminating testing anti-patterns such as reflection-based tests or shared mutable state.
This should trigger for requests such as Review Java code for unit tests; Apply best practices for unit tests in Java code; Write fast JUnit unit tests for Java code; Improve Mockito-based Java unit tests; Refactor Java tests to isolate collaborators.
Part of Plinth Toolkit
Similar popular skills
Related neighbors and high-traction skills in the same topics — useful to compare before installing.
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 compile or mvn compile before applying any change
SAFETY: If compilation fails, stop immediately and do not proceed — compilation failure is a blocking condition
VERIFY: Run ./mvnw clean verify or mvn clean verify after 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
Write fast JUnit unit tests for Java code
Improve Mockito-based Java unit tests
Refactor Java tests to isolate collaborators
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).
