Refactor Axial Expansion

[albeanth]

What is the change?

This PR does a fairly large refactor of the axial expansion functionality in ARMI. A new directory is structure is created to enable better traceability with testing and general maintainability.

Original:

armi/reactor/converters/
|-- axialExpansionChanger.py

and unit tests:

armi/reactor/converters/tests
|-- test_axialExpansionChanger.py

New:

armi/reactor/converters/axialExpansion
|
|-- assemblyAxialLinkage.py
|-- axialExpansionChanger.py
|-- expansionData.py

and unit tests

armi/reactor/converters/axialExpansion/tests
|
|-- test_assemblyAxialLinkage.py
|-- test_axialExpansionChanger.py
|-- test_expansionData.py

Notes:

1. though there are a lot of diffs in the "Files Changed" tab, no new functionality is added.
2. the original testing file had lots of "integration" tests within it. Those are kept and smaller accompanying unit tests are added here.
3. to reviewers: if you want me to try and interactive rebase this or split it up into multiple PRs, let me know.

This does include the changes from PR #1427.

Why is the change being made?

1. The original axialExpansionChanger.py file was responsible for too many things. It was ready to be split up to improve maintainability.
2. The original test_axialExpansionChanger.py was likewise too big and doing too much. It has now been split up and is easier to maintain.

---

Checklist

• This PR has only one purpose or idea.
• Tests have been added/updated to verify that the new/changed code works.

• The code style follows good practices.
• The commit message(s) follow good practices.

• The release notes (location doc/release/0.X.rst) are up-to-date with any important changes.
• The documentation is still up-to-date in the doc folder.
• The dependencies are still up-to-date in pyproject.toml.

[john-science]

1. I think this needs a release note. It's a non-trivial re-write.
2. How much does the Axial Expansion API change? (For people writing code downstream, does this change the API at all?)

[albeanth]

1. I think this needs a release note. It's a non-trivial re-write.

Yes. I will add one once we get further into the review.

2. How much does the Axial Expansion API change? (For people writing code downstream, does this change the API at all?)

The API actually should not have changed at all actually. At least not to that I can remember off the top of my head. I am going to run this on the slough of internal tests though to confirm.

[albeanth]

The API actually should not have changed at all actually. At least not to that I can remember off the top of my head. I am going to run this on the slough of internal tests though to confirm.

The API for unit testing did change. And the refactor changed some imports downstream. So there is an another (minor) downstream PR.

[albeanth]

@john-science @keckler giving a bump on this.

just started doing QA work for the axial expansion changer and it would be really nice to push this through. the improved unit testing and accompanying refactor will help keep things clean imo.

happy to chat offline too.

[john-science]

Put something on my calendar for this, @albeanth

[albeanth]

Put something on my calendar for this, @albeanth

I'll put something on your calendar for next week. Some of the downstream testing is freaking out. I have no idea why and don't have enough time to figure it out this week unfortunately...

[albeanth]

Note to reviewers: this was moved to test_expansionData.py

[albeanth]

@john-science an update -- this PR is blocked by some downstream work but is in line to be completed. Fingers crossed it's finished soon!