Add Unit Tests

[lambrou]

Requesting to be the assignee on this issue.

[softboyjimbo]

That'd be great. Thank you @lambrou

[Czechh]

@lambrou I'll start setting up the code so it's easily testable. And start writing some tests - we can divide an conquer if you'd like. To avoid collisions I'll make a list and work one by one that way if you're handling one specific test I can skip it!

Tasks:

• [ ] Project structure for testing [Sergio]
• [ ] Health check
• [ ] Retrieval
• [ ] POST memory
• [ ] GET memory
• [ ] DEL memory
• [ ] Compact units