I agree that the real test is how well you do on the real codebase. But (as an interviewer) I'm not going to let you see that codebase or spend time describing its architecture to you until I'm convinced you are worthwhile. Hence, walk me through the steps to generate something programmatically; Pascal's triangle or anything else. I don't give a shit that you found code for it on Google, I'm not looking for a solution - I'm looking to understand how well you can solve problems.