JSDoc for test/*

[Computroniks]

Description

Related to #1499

This PR adds JSDoc comments for the test/* directory. For the full TODO list, see #1499

Type of change

Please delete any options that are not relevant.

• Other

Checklist

• My code follows the style guidelines of this project
• I ran ESLint and other linters for modified files
• I have performed a self-review of my own code and tested it
• I have commented my code, particularly in hard-to-understand areas
  (including JSDoc for methods)
• My changes generate no new warnings
• My code needed automated testing. I have added them (this is optional task)