- what will be the output of this few lines of code?
- what will be the size of this structure in memory?
- what is wrong with this code snippet?
- try to refactor this code snippet
- look at this class; how would you add a unit test to test this function?
- after running this program, explain why it prints this output
Ideally, these questions would be answered by using a simple compiler and editor during the interview. Developers don't program on paper in their jobs (at least no longer). If they want to learn something about the traits of the code, they lean on the compiler (for example, print size of a structure, instead of calculate it in your mind).
As you could have infer from this short opinion, I am also not in favor of automated, on-line coding tests. They are not done on paper, which is good, but they focus too much on exact answer, oftern numeric, instead of other important abilities, such as writing concise code.