Unit Test Utility Methods

This generates JUnit 5 test patterns for utility classes and static methods where you don't need mocks. It covers the usual suspects: string manipulation, math helpers, validators, collection utilities. You get AssertJ assertions and parameterized test examples for testing null handling, edge cases, and boundary conditions. The skill pushes you toward descriptive test names and actually testing empty strings, whitespace, and max values instead of just happy paths. It's straightforward for pure functions but includes a rare Clock example when you do need a dependency. The constraints section is honest about floating point comparisons and thread safety, which saves you from common mistakes.