It tightly couples domain needs with implementation details. Thinking of it as a leaky abstraction helps me. I try hard to separate domain logic tests from im

It tightly couples domain needs with implementation details. Thinking of it as a leaky abstraction helps me. I try hard to separate domain logic tests from implementation specific tests. Your code could be loosely coupled with high cohesion, but with lots of random tests like you get when code coverage is a performance metric, you have to add a lot of complexity that only relates to an implementation.