Prevent duplicate default SSLContext instances

[vexofp]

needs #105362

Proposed change

This PR fixes the unintentional duplication of default SSLContext instances created in util/ssl.py (#105115), when the factory methods are called both with and without explicitly passing the default cipher list. The root cause of this behavior is that the @functools.cache decorator does not play nicely with default arguments. While the performance/efficiency impact of these duplicate contexts is quite small, so is the fix. 😄

The approach taken was to move the implementation and caching into private functions that do not have a default argument value. There are no changes to the actual implementation. The existing public functions now call those private functions, always passing in the argument explicitly to ensure reliable cache behavior. The public functions maintain their existing signatures (including the defaulted argument value), so there is no change to the public API.

A new test was added to verify the caching behavior.

The change in imap/coordinator.py is to resolve a mypy warning that cropped up. I suspect the @cache decorator was obscuring some of the type information previously. Now that it is removed from the public functions, mypy correctly caught that a str was incorrectly being passed where an enumeration value is required.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes Duplicate default SSLContext instances #105115
• This PR is related to issue:
• Link to documentation pull request:

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[home-assistant]

Hey there @jbouwh, mind taking a look at this pull request as it has been labeled with an integration (imap) you are listed as a code owner for? Thanks!

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[vexofp]

CLA signed! 🖊️

Stale

[bdraco]

This looks like a good fix. Please split it into two PRs so it can be backported

One for imap
One for the util

[vexofp]

Okay. I split the IMAP change off into #105362 and left only the util changes in this PR.

I guess that one will need to go first, then? In the meantime, this one is going to fail mypy due to that issue.

[bdraco]

Thanks @vexofp