Hide a testcase from the student
I have noticed that students can see all the test cases, that are being checked by looking at the tests folder. Is there a way to hide the tests from the student?
If you want students to reason about the expected output before seeing them, you can use the "locking" feature of OK (See the paper here for it's effectiveness: http://denero.org/content/pubs/las15_basu_unlocking.pdf)
If you're ok exposing the input but not the output, you can wrap it an another layer of hashing. Here's one way we've done that: http://denero.org/content/pubs/las16_sridhara_fuzz.pdf
If you fully want to hide the existence of a test case, you'll have to use server side auto-grading (and not client side scoring). It's pretty hard to fully hide what a program is executing (because end users control the code)