Testing is real coding! It's just not glamorous, but testing is one thing that every developer should do although many don't. Maybe you could carefully refactor

Testing is real coding! It's just not glamorous, but testing is one thing that every developer should do although many don't. Maybe you could carefully refactor scary parts of the code base after writing lots of tests for it. Like others have said, make a case for the refactor to your direct report. Good luck!