API integration tests

[psilabs-dev]

I recommend adding some kind of testing on the controller level, in addition to plugin testing, as we see more non-plugin related commits.

Controller level (specifically API) calls are most exposed to the client and are not expected to change. Testing them tests many components of the library. I think this is a good place to start, and we can do one API at a time. I would also be willing to contribute, after understanding the code more.

Anyhow this needs fleshing and is more of a long term topic (realistically several months lol), so I'm putting this as a discussion.