"Can you work on this ticket? It's kind of urgent."

-- "OK"

"And could you please not refactor? Just get this done."

-- "Why? What's the issue?"

"The logic is complex. We should not break it."

-- "Erm, that's what the tests are for. So yes, if the need arises, I'll refactor. The tests are my guidelines if the logic breaks or not."

There's a reason we create tests. So let's not hinder code base improvements by some random fear that stuff might break.

If breaks due to refactoring, we'll fix it by adding a valid test case during and then fixing the bug.

If my refactoring does not break the tests, I'll assume the code base is stable.

If your code is untested, then we have a complete different problem.