Agreed that asserting ``resetOriginalReadPreference()`` is the last method called would probably make things too brittle.

Although do you agree that asserting `resetOriginalReadPreference()` as the first method is still a good thing?  The first action in a save operation should be to ensure we are only reading from primary.  If a future code change alters this then having a test that will fail should cause the developer to think carefully about why they have made this change.