Add Student Controller Tests

[sophiacrennan]

Problem: We need to add student controller tests
Solution: Using the Course Controller as an example, write tests

Description: Since we now have a testing framework, it's time to write tests for all our controllers! You can use the testing documentation and the course controller tests as an example to write the student controller tests.

Specs:

• write tests for each method in the student controller
• document any issues you had that others might encounter and document the solution

Notes
This will be the biggest ticket for testing controllers. Would probably be a good idea to start with a smaller controller first.

If blocked, contact @VKong6019