131-java-testing-unit-testing

What problem does it solve?

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. Part of the skills-for-java project

Core Features & Use Cases

• Migrate from JUnit 4 to JUnit 5 with Jupiter extensions and modern annotations
• Adopt AssertJ for fluent assertions and Mockito for mocking
• Apply Given-When-Then structure, parameterized tests, and boundary-condition checks (RIGHT-BICEP, CORRECT, A-TRIP)
• Target Java unit testing guidelines across typical enterprise projects
• Use in real-world projects to improve test clarity, stability, and maintainability

Quick Start

Migrate existing tests from JUnit 4 to JUnit 5 and begin using AssertJ and Mockito in your test suite.