unity-testability

To make Unity MonoBehaviour code testable, separate algorithmic pure C# logic from engine-dependent scene state and Transform interactions. Extracting logic into plain classes allows reliable mocking and fast unit testing without runtime behavior changes.

EditMode tests validate isolated pure C# logic quickly without loading the Unity scene, while PlayMode tests verify scene interactions and MonoBehaviour behavior. Separating algorithmic logic from engine state lets you cover pure logic in EditMode and scene dependencies in PlayMode.

Isolate GameObject and static global dependencies by introducing seams like plain service classes, strategy interfaces, and data-transfer objects. This refactoring decouples your algorithmic logic from Unity engine state, enabling straightforward dependency injection and mocking for unit tests.

Keep a thin MonoBehaviour when the class primarily manages direct scene state or Transform manipulation. Extract algorithmic logic into pure C# classes when it lacks engine dependencies, ensuring that Unity-facing components remain lightweight wrappers for testing purposes.

Yes, you can refactor Unity C# scripts for testability without modifying runtime behavior by extracting pure logic into separate classes and introducing interfaces. This approach ensures the game runs identically while making the underlying logic available for EditMode tests.