Medium Model Tests

[NicholasLYang]

We need tests for the medium model. These need to test the functionality of a medium. Thus, they need to test uploading, getting S3 URLs and deleting. They should be written using rspec in spec/models/medium_spec.rb.

The tricky part of this is figuring out precisely what needs to be tested and how you can test it. For this, feel free to consult me.

The basic idea of tests is that they should serve as:

A. Living documentation. What the test says, the code should do. You should be able to read the tests and understand how the code works.
B. A way of ensuring correctness. If tests pass, then we can be reasonably sure that the code works and is deployable.
C. A method to ensure airtight interfaces. This is a bit of a tricky concept, but in software development we have the idea of interfaces, basically the borders between different parts of the program. It's important that we understand how these interfaces are designed and how each piece interacts with its neighbors.

This is not an easy issue. It's completely open ended and up to your discretion. But if you complete it, it'll be a big boon for the entire codebase.

[AndySok]

not sure if this was ever completed or not, @NicholasLYang @jsonkao @DJankauskas @vs2961 has any of you worked on this, or is this still an issue we should work on?