This was an insightful comment. I shouldn't write tests that assert a method on my mock has been called, I should design a mock whose behaviour changes in respo

This was an insightful comment. I shouldn't write tests that assert a method on my mock has been called, I should design a mock whose behaviour changes in response to interaction, and then assert that the relevant behaviour has indeed changed! That change would still be the same amount of maintenance (if the underlying implementation changes, the mock will have to be updated to reflect that as well) but the test will communicate more clearly what the intention of the interaction is.