@Kulgar sorry to be so slow responding to this.  The tests should probably go in spec/models/assignment_spec.rb.  You can probably look around in that file to get a sense of the helpers we have to build up a course with an assignment.  There's also a `context "peer reviews"` section in that file that will probably be helpful.  Finally, if you look in spec/models/course_spec.rb and search for "gradebook_to_csv" you can see how we test the gradebook export.