Someone who is genuinely good at writing code should be able to produce code that has no or very few bugs. Similarly, they should be pretty good at inferring what is wrong in the rare case of bugs by simply running the program. Therefore, they would find writing unit tests and similar rituals unnecessary and time consuming.

They would most probably write specialized tests where appropriate to catch subtle bugs that elude even their superior skills. This would be a matter of personal judgment based on the problem at hand.