Code coverage basics for pytest

[FlorianDeconinck]

Description
Our test code coverage is unknown at this time. First step is to compute and display the code coverage, which this PR does.

How Has This Been Tested?
N/A

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included

[oelbert]

👍