tests: replace function-scoped helper fixtures with TestHelper

[snejus]

• Test setup was consolidated into shared helper classes instead of using local helper fixtures.
• test/library/test_migrations.py now uses MigrationTestHelper to provide one common migration harness, with each test class defining only the legacy state and migration it needs.
• Plugin tests in test/plugins/test_fuzzy.py, test/plugins/test_missing.py, and test/plugins/utils/test_playcount.py now rely on shared helpers like PluginTestHelper and TestHelper for common setup.

Note: I kept these fixtures in these files

• test_query.py
• plugins/test_random.py
• plugins/test_aura.py
• plugins/test_lyrics.py

because they intentionally use a higher scope, for example in test_query.py:

@pytest.fixture(scope="class")
def helper():
    helper = TestHelper()
    helper.setup_beets()

    yield helper

    helper.teardown_beets()

Using this setup pattern in test_query.py significantly improved testing durations.

Architecture impact

• Test infrastructure now follows a clearer base-class pattern for shared setup.
• Migration tests cleanly separate 'prepare old state' from 'run migration and verify result'.
• Plugin tests now use the same setup path, which makes new tests easier to add and keeps test structure more consistent across files.

High-level outcome

• Less duplicated fixture boilerplate.
• More consistent and easier-to-read test architecture.
• Tests stay focused on behavior being verified, which should make maintenance and future extension simpler.

[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

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.71%. Comparing base (60047df) to head (3f4d9d5).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6709      +/-   ##
==========================================
+ Coverage   74.52%   74.71%   +0.18%     
==========================================
  Files         162      162              
  Lines       20818    20818              
  Branches     3295     3295              
==========================================
+ Hits        15515    15554      +39     
+ Misses       4547     4505      -42     
- Partials      756      759       +3     

see 1 file with indirect coverage changes

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[Copilot]

Pull request overview

grug see PR make test setup less copy-paste. instead of local helper fixtures per file, tests now inherit shared helper classes (TestHelper/PluginTestHelper) and migration tests get one common harness.

Changes:

• swap function-scoped helper fixtures for TestHelper / PluginTestHelper base classes in plugin tests
• add MigrationTestHelper harness so each migration test only defines legacy setup + migration under test
• adjust playcount tests to use class-based helper + explicit log fixture injection

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
test/plugins/utils/test_playcount.py	move from helper fixture to TestHelper inheritance; pass logger via fixture
test/plugins/test_missing.py	use shared PluginTestHelper (plus IO mixin) for missing plugin CLI tests
test/plugins/test_fuzzy.py	use PluginTestHelper for fuzzy plugin tests; remove local helper fixture
test/library/test_migrations.py	introduce MigrationTestHelper and refactor migrations tests onto shared harness

[Copilot]

Pull request overview

Copilot reviewed 19 out of 19 changed files in this pull request and generated 1 comment.

[semohr]

I like the introduction of these <scope>_helper fixtures in general. I'm just not entirely sure how the scopes were chosen based on where the fixtures are actually used. To me, it looks like most of them could probably use session scope. 🤔

I did a quick experiment and changed the fixture in test_random to session, and I didn't run into any issues. Maybe there's a reason for the more restrictive scopes that I'm missing?

[semohr]

Why the indirection? Couldn't we use session_helper directly?

[snejus]

The indirection is intentional: it keeps each test module using the stable local helper fixture name while delegating lifecycle/scope to the shared helper fixtures. That means the rest of the module does not need to know whether the backing helper is session-, module-, or class-scoped.

If we used session_helper directly, that scope detail would spread through the module and future scope changes would require broader fixture/test renames. With this shape, changing scope requires adjusting these 3 lines only:

@pytest.fixture(scope="session")
def helper(session_helper):
    return session_helper

[semohr]

Same here again some unneeded indirection imo. Im also wondering now why we need the helper on different scopes in the first place. Have you tried session scope here? Do we have sideffect here which we dont want to propagate to the session scope?

[semohr]

Maybe we add a bit of doc strings here on when we expect them to be used?