typing: add types to beets.util and beets.test.helper

[snejus]

I've started working on migrating the codebase to pathlib.Path and this is the very first step: fully type beets.util and beets.test.helper. Next, I will me migrating tests to use pathlib.Path.

• Extracts shared path/temp-directory behavior into PathsMixin, and splits import-specific test setup into ImporterMixin. This makes beets.test.helper more modular and gives test helpers a clearer inheritance structure.

• Updates TestHelper and import helpers to use those smaller mixins, while keeping existing test behavior intact. The main architectural effect is better separation between core test setup, filesystem helpers, and importer-specific utilities.

• Tightens typing across beets.test.helper and beets.util, especially around path handling. beets.util now accepts a broader set of path types through PathLike/AnyPath, which reduces friction between bytes, str, and Path usage.

• Aligns helper internals with the typed interfaces by normalizing path handling in methods like touch, using typed template(...) entries for importer path formats, and fixing a few return-type/inheritance edge cases.

• High-level impact: this is mainly a typing and test-infrastructure cleanup. It improves maintainability and type-checker accuracy without changing production architecture or intended runtime behavior.

[github-actions]

Thank you for the PR! The changelog has not been updated, so here is a friendly reminder to check if you need to add an entry.

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.80%. Comparing base (76113c1) to head (9232a66).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
beets/util/__init__.py	85.71%	3 Missing ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##           speed-up-tests    #6805      +/-   ##
==================================================
- Coverage           74.98%   74.80%   -0.19%     
==================================================
  Files                 163      163              
  Lines               20966    20967       +1     
  Branches             3302     3302              
==================================================
- Hits                15721    15684      -37     
- Misses               4486     4527      +41     
+ Partials              759      756       -3     

Files with missing lines	Coverage Δ
beets/util/__init__.py	79.27% <85.71%> (+0.04%)	⬆️

... and 2 files with indirect coverage changes

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[Copilot]

Pull request overview

PR try make first step toward pathlib.Path migration by adding typing to beets.util and beets.test.helper, plus split test helper behavior into smaller mixins (PathsMixin, ImporterMixin).

Changes:

• Add tighter type hints in beets/util/__init__.py and widen some path-accepting APIs to PathLike.
• Refactor beets/test/helper.py into smaller mixins and update helper methods to normalize path handling.
• Adjust importer test helper setup to use typed template(...) for lib.path_formats.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
beets/util/init.py	Type annotations on filesystem helpers; small behavior-neutral cleanup in move() typing comments.
beets/test/helper.py	New mixins + typing; path normalization changes in helpers; importer helper setup updated.

[semohr]

Looks good from my perspective.

Consider adding the files to the optin stricter mypy config.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

[snejus]

Consider adding the files to the optin stricter mypy config.

I tried adding them:

diff --git a/setup.cfg b/setup.cfg
index 01971c01d..259e8a5c0 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -55,6 +55,12 @@ check_untyped_defs = true
 disallow_untyped_decorators = true
 check_untyped_defs = true
 
+[[mypy-beets.utils]]
+strict = true
+
+[[mypy-beets.test.helper]]
+strict = true
+
 [[mypy-beetsplug.musicbrainz]]
 strict = true

And ran mypy on master but it didn't complain about any issues :/

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

[semohr]

Consider adding the files to the optin stricter mypy config.

Maybe using disallow_untyped_defs would work? Am also not sure the config is picked up correctly 🤔

My idea here was just to have future changes require stricter rules for these files as they are typed properly right now.