Initial view model state is taken from MockStateHolder and used in ViewModel creation. Additionally, any changes to state during ViewModel initialization are forcibly overridden by the mocked state.

Generally uses the same behavior as None, however, if an 'existingViewModel' is accessed and no previous instance exists this will take the default mock state off of the Fragment for that ViewModel and initialize the ViewModel with that state.

This is useful when we want a mocked screen to be able to open non mocked screens (in a test), and would otherwise crash if a newly opened screen uses 'existingViewModel' and the viewmodel doesn't actually exist (because we came from a mocked screen that doesn't represent normal screen flow).