unity-testability

To unit test MonoBehaviour logic without scene state, you isolate algorithms from MonoBehaviour and scene-dependent APIs by moving them into pure C# classes, allowing execution without Transform, GameObject, or scene dependencies.

The best way to separate business logic for EditMode tests is to identify seams and interfaces that isolate dependencies, using config injection and adapters for Unity APIs to map logic boundaries to pure C# versus Unity-facing code.

Yes, you can use dependency injection to improve Unity PlayMode test coverage by decoupling runtime decision logic from scene state, creating testable seams that allow isolated verification of dependencies and algorithms.

To decide which responsibilities to move into pure C#, you review your class to map logic boundaries, keeping Unity-facing code minimal while extracting algorithms into plain C# so they can run without Transform or GameObject references.

EditMode tests fail when depending on GameObject properties because Unity scene-dependent APIs are entangled with business logic, requiring you to isolate algorithms into pure C# and use adapters to remove direct Transform or scene state dependencies.