Get test coverage back to 100%

[CLeeSpruit]

Describe current status
With the recent switch from jest -> ava and slew of refactors, a lot of tests had to be scrapped or rewritten. No more 100% coverage. 😢

Describe the outcome you'd like
With a smallish library like this, 100% isn't impossible. This time around I think some integration tests are in order. Unfortunately with the unit tests we had, they were somewhat fragile because there is so much dependency between classes that any sort of refactoring or clean up caused most of them to break.

Additional context
...