Back-end tests for one of the controllers

[skassam21]

• Take a look at our testing tutorial - https://docs.google.com/presentation/d/18O0Yojq976gnwWCkfXWEC8o4lBOg42DjuS4Xf3YzCvk/edit#slide=id.p
• Try to write a few back-end tests for one of the models (i.e. signup/signout, interviews, feedback routes, etc.)
  • you will need to write integration tests (so testing one route and one path at a time)
  • you will need to "mock"/"stub" the mongo db - see mongodb-memory-server - this is so that you don't use a development or live database for tests - see https://dev.to/paulasantamaria/testing-node-js-mongoose-with-an-in-memory-database-32np