Extend type hints to tests

[JoeZiminski]

Currently, type hints are not added to tests to avoid the maintenance burden, and mypy does not check the tests. In general, it would be nice to have type hints on tests, espsecially where they aid in reading. This is particularly important for some cases, see here.

In a new PR, we can start by:

1. extend mypy to cover tests
2. start adding type hints where useful, here first.
3. extend developer docs to explain the situation

[ishan372or]

Hi, @JoeZiminski i would like to work on this, Would you prefer I open a single PR once all three tasks (hints, mypy config, and docs) are complete, or would you like me to submit an initial PR just for the SSH type hints to ensure I'm on the right track?

[JoeZiminski]

Hi @ishan372or thanks for this, it's up to you but because it is such a huge job, I think it would make sense to set up mypy to run on the tests, and see if it throws any errors. Then maybe type-hint one or two files and see how it goes. Unfortunately these are many tests to type hint, and it can take a long time, so even hitting a few at this stage would be useful.

The section that excludes tests from mypy is here. Just removing this line should start mypy checking the tests for type errors. You can run with:

pre-commit run mypy --all-files

If your not so familiar with typing it can take a bit of time to get used to it. Please let me know if you have an questions!

[ishan372or]

Thanks @JoeZiminski for the clarification. I’ll start by enabling mypy for tests by removing the exclusion and running pre-commit run mypy --all-files to get a baseline of the current errors.

Then I’ll focus this PR on type-hinting a small, representative subset of tests (likely 1–2 files around the SSH transfer tests you mentioned) to understand the common patterns