a) At my uni 15 yrs ago. Write a code that listens on certain input. You upload the source code, a bot compiles it, runs a bunch of functional test, then it tells your score. It didn't help what you missed, just a score, like Your solution passed 225 test out of 250.

b) Find a bug in a source code. Describe the end-user captured bug, and measure the time and the quality of the solution.

c) Simulate a distributed code review and measure the found problems. This can be extended to UX as well.

(These are just quick examples.)