I agree. There are tons of ways to test for this. Write a simple library that doesn't use any good design principles and have your candidate spend some time re

I agree. There are tons of ways to test for this. Write a simple library that doesn't use any good design principles and have your candidate spend some time refactoring it. You can even use the same library multiple times. Heck, have your senior engineers also do this, so that you can get a good baseline for what an ideal candidate should come up with.