Move triple-container tests from test_extra to nested test files.

[jackdewinter]

Prerequisites

• Are you running the latest version of this application?
• Have you checked the Frequently Asked Questions document?
• Did you perform a cursory search of other issues to look for related issues?

Feature Request

Description

The test_extras.py file is a bit of a dumping ground. Start to move some of the more massive test sets to their proper triple nested test files.

Desired Behavior of Feature

See Above.

What Are the Benefits of This Feature?

Make the tests more maintainable, less bulky with all sorts of nested tests in that one file.