I'm trying to create an auto-grader for one of my beginning programming courses for python. From my online search, I've come to know that it is effectively a unit test framework that tests the student's code rather than production code but I'm not really sure how to structure the flow of the program. Can anyone please provide a strategy for submission of code by students and automating the whole process of marking?

For instance, how would the student code be submitted and then stored/structured on disk, how would the grades be stored/reported?

I'm only looking for a broad strategy and will try on my own to fill in the blanks.

(I asked this on stockoverflow.com initially but it's considered as off-topic and I was suggested to ask here.)