This is always the theory: "well pull that out into a separate class with a public API". But then those classes end up only being used in one place (the class i

This is always the theory: "well pull that out into a separate class with a public API". But then those classes end up only being used in one place (the class it was extracted from), with a totally unnecessary increase in public API surface area. Both the extra verbosity and the pointless increase in API surface area are worse than just writing unit tests against private functions IMO.