In the case of CS100.1X, you had to submit the program to an online grader. However, the assignment contains test cases; if all your test cases pass, then you'd most likely pass the online grader.

However, if you changed the variable names, like in the article, the test cases would fail...unless you changed them in the test cases itself. In which case, the test cases would definitely fail in the online grader.

I took the Andrew Ng Coursera class which had an online grader that had test cases as well, but mostly it was just defining functions with specified input and outputs, so you're free to use whatever style guide you want in between. (CS100.1X does have a few of those, and they are easily the most difficult part of the assignment since it requires Python shenanigans)