Create sample unit test to assist developers

[GeorgeGayno-NOAA]

Unit tests are now required before any changes can be merged. When developers are told this, their first question is: "How do I create a unit test and run it under Github actions?" Then, I write a basic test for him. If we had a sample, working test baselined under the repo, it would serve as a guide for developers (and save the admins a lot of time).

[kgerheiser]

Maybe a README.md in the tests directory with a brief explanation of what a unit test should do (exercise the code, check results), and a sample (or point to a simple test like tst_quicksort)?

[edwardhartnett]

I suggest pointing such users at an existing test which most closely matches their proposed test. That will get easier as tests are added.

Adding a section to the README: "How to Add a Unit Test" would be a good idea.

[GeorgeGayno-NOAA]

Reopen so @LarissaReames-NOAA can add her sample unit test.

[GeorgeGayno-NOAA]

Merged to 'develop' at 7c31411.