Add database updates test

Problem/Motivation

If database updates are ever needed, it can be helpful to have testing infrastructure in place to be able to test them.

This involves capturing the database tables specific to the module as a fixture, so the tests can run the upgrade and compare the before/after results.

(note this ticket is split from ✨ Add automated tests Active )

Proposed resolution

Figure out how to capture the database tables. Create a fixture. Add an example test.

Remaining tasks

1. Write a patch
2. Review and feedback
3. RTBC and feedback
4. Commit

User interface changes

None.

API changes

None.

Data model changes

None.