TRD: Outline Standards for Unit Testing

[StephenRiosDev]

Currently, our unit tests are quite verbose, and are written in a way that tests multiple pieces of functionality at once.

For instance, select tests menu's implementation of keydown handlers and selection by using manually fired keyboard events to attempt to manipulate the menu in order to test various features. This means that tests that do this test multiple features in menu despite the fact that the test is supposed to be for select, so we are not only testing multiple pieces of functionality, we are doing so across multiple components.

This discussion is to define an agreed-upon standard to be followed by all engineers when adding or updating unit tests in the future to improve test quality, stability, and specificity.