Test for edit notifications

I completed the tests for edit Notifications.

I selected the Notifications collection for tests because it was the easiest thing. I tried to figure out the entire logic of app, but found that I can't understand some permission rules for now. I need to look into the code bit more careful. Also I think that I have not enough information about data structure in the DB. I found schema explanations in two places in the code, and for example I see that only "name" field is described for Students. I think I could to extend this schema and seed the DB by the right data, but I afraid to do it right now without your acceptance :)