An Engineer with this core skill must be able to demonstrate good Test Design.
Something about conciseness.
Engineers that consider coupling avoid causing unnecessary code churn induced by too much tight coupling.
If there is one call-site to a particular function then that function is easy to change
It is desirable to ensure that the public interface of production code can evolve at a different rate to the test cases.
Conversely it is not desirable to need to update all your test cases to change the public interface