Damn this looks like magic to me. Need to investigate and possibly look into these tests with my game due to how interactive I want it to be, without those bugs a bound.
That was the very reason I set this up: I used to break core gameplay functionality accidentally without realising. With those tests it is ensured that everything works as expected.
My tests are a bunch of SceneTree headless Godot scripts… maybe I could refactor them to this. They effectively do that: set the scene, run some scripts, check properties.