Reorganize test files into a tests directory

[jonespm]

This project has a number of test files scattered around the code. It's generally recommended that tests be placed in a directory called "tests" in each app or creating a top level tests and putting them all in there.

Then split split up rather than having everything in a tests.py.

I think we'd like to push toward this into running the tests on a Github Action and making the tests easier to add and extend.