tests that require reading in external files from within test file

[tbrown122387]

If there is a unit test that compares a student variable to some variable created from an external file, usually I'll have to setwd() at the top of my unit test file.

• make requirement more obvious, and
• don't hide error messages when setting working directory fails

[tbrown122387]

The same is true if you are calling out to third party libraries in the test file. If you’re doing tjay you’ll need a library call in there