Test an application using JUnit 4

Nobody has claimed this yet.

## User story:
As a user of this test framework, I want to test my application using JUnit 4 because I already have significant investment in JUnit 4 and do not wish to migrate to JUnit Jupiter.

## Additional detail:
JUnit Jupiter is the newest version of JUnit and has a good amount of adoption. From a test framework implementor perspective, Jupiter is far more flexible and powerful than previous versions of JUnit. By default, we will use Jupiter in implementation and examples, but it should also be possible for users to use JUnit 4 (although it may be a bit clunkier).

Start by examining how the framework currently uses JUnit Jupiter in its implementation and examples, then identify the entry points involved in running user tests. Define the compatibility approach for applications that remain on JUnit 4, and verify that a JUnit 4 application can be tested without migrating to JUnit Jupiter.

Written by the indexing model from the issue text.