Backend returns a private embedded struct of framework.Backend.

ExpectInternalValue checks the internal in-memory value.

Factory returns a new backend as logical.Backend.

FactoryType is a wrapper func that allows the Factory func to specify the backend type for the mock backend plugin instance.

New returns a new backend as an interface.

WriteInternalValue is a helper to set an in-memory value in the plugin, allowing tests to later assert that the plugin either has or hasn't been restarted.