Improve test coverage

[abathur]

Current minimal test coverage is laser-focused on the core workflow (and even then, only as it's intended to be used). Probably worth improving these soon, since they'll make it easier for others to contribute.

---------------------------------------
api.py                 69     42    39%
constants.py            3      0   100%
constellation.py      123     62    50%
input_handlers.py      78     34    56%
---------------------------------------
TOTAL                 273    138    49%```