Author and run the Unity game-engine Test Framework (`com.unity.test-framework`, currently v1.8). Distinct from the ThrowTheSwitch Unity C testing library at throwtheswitch.org/unity - the two tools share only a name. Covers package install via Package Manager, the EditMode vs PlayMode split, the [Test] / [UnityTest] / [SetUp] / [TearDown] / [UnityPlatform] attributes, assembly-definition setup (Editor folder vs asmdef with `includePlatforms` / `optionalUnityReferences: [TestAssemblies]`), Test Runner window, command-line batch invocation with `-runTests` / `-testPlatform` / `-testResults` / `-testFilter` / `-testCategory`, NUnit 3.5 assertion API, and CI integration. Use when the unit under test is C# Unity code that needs to exercise the Unity runtime or editor.