unit-testlisted

# Unit Test Skill This skill focuses on writing fast, isolated tests for individual units of code (functions, methods, classes). ## When to use this skill - When writing tests for utility functions, algorithms, or standalone classes. - When using tools like Jest, pytest, JUnit, or xUnit. - When needing to mock out dependencies (databases, APIs, file systems). ## Guidelines - **Isolation:** A unit test should not rely on an external database or network. Use mocks or stubs instead. - **Naming:** Use clear, descriptive names (e.g., `calculateTotal_withValidInput_returnsCorrectSum`). - **Structure:** Use the Arrange-Act-Assert (AAA) pattern. - **Speed:** Unit tests must be fast so developers can run them frequently.