[FEAT] output file unit tests

[aburrell]

Is your feature request related to a problem? Please describe.
There are no unit tests

Describe the solution you'd like
The creation of a unit test suite.

To start, unit tests for the output files.

Possible test runner: http://cxxtest.com/guide.html
Blog about possibilities: https://www.typemock.com/unit-testing-with-c/

The test for the aether output files would:

Create a file
Test the contest by:
A) using ncdiff (https://linux.die.net/man/1/ncdiff) against saved file
B) opening the file and checking the contents against expected names, dimensions, and values

Describe alternatives you've considered
Not having tests and allowing things to break when things start getting really complicated.

Additional context
We said we'd follow modern coding practices, and this is one of them.