Write unit tests

[jwflory]

Summary

Write unit tests to add support coverage to exporter / importer functionality

Background

Unit tests ensure code remains functional and healthy across changes. It lowers the barrier for contributions and boosts the confidence of potential contributors to make a new change. It also enables different tools such as continuous integration based on unit tests.

Details

Explore pytest again. See test_demo.py locally for an example of how to do this.

Outcome

Project functionality is ensured through unit tests and clear indicators provided when project breaks; increased confidence of new contributors to make changes