Best use case
java-junit is best used when you need a repeatable AI agent workflow instead of a one-off prompt.
Get best practices for JUnit 5 unit testing, including data-driven tests
Teams using java-junit should expect a more consistent output, faster repeated execution, less prompt rewriting.
When to use this skill
- You want a reusable workflow that can be run more than once with consistent structure.
When not to use this skill
- You only need a quick one-off answer and do not need a reusable workflow.
- You cannot install or maintain the underlying files, dependencies, or repository context.
Installation
Claude Code / Cursor / Codex
Manual Installation
- Download SKILL.md from GitHub
- Place it in
.claude/skills/java-junit/SKILL.mdinside your project - Restart your AI agent — it will auto-discover the skill
How java-junit Compares
| Feature / Agent | java-junit | Standard Approach |
|---|---|---|
| Platform Support | Not specified | Limited / Varies |
| Context Awareness | High | Baseline |
| Installation Complexity | Unknown | N/A |
Frequently Asked Questions
What does this skill do?
Get best practices for JUnit 5 unit testing, including data-driven tests
Where can I find the source code?
You can find the source code on GitHub using the link provided at the top of the page.
SKILL.md Source
# JUnit 5+ Best Practices
Your goal is to help me write effective unit tests with JUnit 5, covering both standard and data-driven testing approaches.
## Project Setup
- Use a standard Maven or Gradle project structure.
- Place test source code in `src/test/java`.
- Include dependencies for `junit-jupiter-api`, `junit-jupiter-engine`, and `junit-jupiter-params` for parameterized tests.
- Use build tool commands to run tests: `mvn test` or `gradle test`.
## Test Structure
- Test classes should have a `Test` suffix, e.g., `CalculatorTest` for a `Calculator` class.
- Use `@Test` for test methods.
- Follow the Arrange-Act-Assert (AAA) pattern.
- Name tests using a descriptive convention, like `methodName_should_expectedBehavior_when_scenario`.
- Use `@BeforeEach` and `@AfterEach` for per-test setup and teardown.
- Use `@BeforeAll` and `@AfterAll` for per-class setup and teardown (must be static methods).
- Use `@DisplayName` to provide a human-readable name for test classes and methods.
## Standard Tests
- Keep tests focused on a single behavior.
- Avoid testing multiple conditions in one test method.
- Make tests independent and idempotent (can run in any order).
- Avoid test interdependencies.
## Data-Driven (Parameterized) Tests
- Use `@ParameterizedTest` to mark a method as a parameterized test.
- Use `@ValueSource` for simple literal values (strings, ints, etc.).
- Use `@MethodSource` to refer to a factory method that provides test arguments as a `Stream`, `Collection`, etc.
- Use `@CsvSource` for inline comma-separated values.
- Use `@CsvFileSource` to use a CSV file from the classpath.
- Use `@EnumSource` to use enum constants.
## Assertions
- Use the static methods from `org.junit.jupiter.api.Assertions` (e.g., `assertEquals`, `assertTrue`, `assertNotNull`).
- For more fluent and readable assertions, consider using a library like AssertJ (`assertThat(...).is...`).
- Use `assertThrows` or `assertDoesNotThrow` to test for exceptions.
- Group related assertions with `assertAll` to ensure all assertions are checked before the test fails.
- Use descriptive messages in assertions to provide clarity on failure.
## Mocking and Isolation
- Use a mocking framework like Mockito to create mock objects for dependencies.
- Use `@Mock` and `@InjectMocks` annotations from Mockito to simplify mock creation and injection.
- Use interfaces to facilitate mocking.
## Test Organization
- Group tests by feature or component using packages.
- Use `@Tag` to categorize tests (e.g., `@Tag("fast")`, `@Tag("integration")`).
- Use `@TestMethodOrder(MethodOrderer.OrderAnnotation.class)` and `@Order` to control test execution order when strictly necessary.
- Use `@Disabled` to temporarily skip a test method or class, providing a reason.
- Use `@Nested` to group tests in a nested inner class for better organization and structure.Related Skills
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