unit-test-utility-methods

JUnit 5 patterns for testing utility classes, static methods, and pure functions without mocking complexity. This skill generates tests for utility classes with static helper methods and pure functions. It provides patterns for testing null handling, edge cases, boundary conditions, and common utilities like string manipulation, calculations, data validation, and collections. Pure functions require no mocking. Use this skill when: - Covers testing strategies for string manipulation, calculations, collections, data validation, and format utilities with edge case and boundary condition handling - Uses AssertJ assertions for readable test code and @ParameterizedTest for testing multiple similar scenarios efficiently - Emphasizes null handling, empty inputs, extreme values, and floating-point precision as critical edge cases - Includes best practices for pure functions, descriptive test naming, and avoiding over-mocking in utility testing - Writing tests for utility/helper classes with static methods - Testing pure functions with no state or side effects - Testing string manipulation, formatting, or transformation utilities - Testing calculation, conversion, or math helper functions - Testing data validation and formatter utilities - Verifying null/empty input handling in utility code - Testing collections or array helper methods - Create test class : Name it after the utility...