[FEATURE] Add test coverage metrics

[sondavidb]

Description

We know that our testing suite, while somewhat comprehensive, lacks in a few areas. It would be great future-proofing to ensure that we have good testing coverage that anyone can easily run.

Describe the solution you'd like

A Makefile target that will test for code coverage. Ideally this gets called in our workflow as well.

Describe any alternative solutions/features you've considered

None shy of manual debugging

Any additional context or information about the feature request

Once this is implemented, we can be more rigorous on tackling certain issues related to testing coverage. #290, #569, $570, #571 are all currently open as of opening this issue.