Write Tests using a manageable approach

[marcoarthur]

Since test files are becoming confusing, and selection of tests to run is becoming an ugly mess. We want to separate
tests into unity/integration/regressions and use a better approach. Main goals are:

1. have a decent structure to be able to separate concerts
2. have a way to turn on-off tests without commenting lines
3. maybe incorporate a test framework. Have to think about it.
4. produce test coverage.
5. automate github action to test it