Review and improve test coverage

[danswick]

The FAC application's unit tests have gone through a couple of iterations in the last two years. Most recently, we went from relaxed test coverage thresholds (during rapid development) to more strict coverage standards. We've also changed our automated CI/CD coverage reporting to use a tool that provides less verbose updates (examples of before and after).

While it's good to enforce a coverage standard, there is still room to improve. This ticket tracks work related to getting our coverage percentage up. The basic phases will likely be:

Basic steps

Beta Give feedback

1. Review current coverage reports and identify top opportunities to improve coverage.
2. For the opportunities identified above, add/improve unit tests.
3. Update our test threshold to match the new coverage level.
4. Create guidance for test covarage requerements.