What problem does it solve? Writing consistent, maintainable unit tests in C# requires knowing NUnit's attributes, assertion styles, and data-driven testing features, which developers often apply inconsistently across a codebase. ## Core Features & Use Cases - Test Structure Guidance: Enforces conventions like the Arrange-Act-Assert pattern, [TestFixture]/[Test] attributes, and the MethodName_Scenario_ExpectedBehavior naming pattern. - Data-Driven Testing: Covers [TestCase], [TestCaseSource], [Values], [Range], and combinatorial approaches for parameterized tests. - Assertions and Organization: Recommends the constraint model with Assert.That, exception assertions, categories, and setup/teardown lifecycle hooks. - Use Case: When adding tests for a new Calculator class, use this Skill to scaffold a CalculatorTests fixture with proper setup, parameterized test cases, and constraint-based assertions. ## Quick Start Help me write NUnit unit tests for my C# class using data-driven test cases and the Arrange-Act-Assert pattern.