Fix plugin loading (#6039)

Fixes #6033

This PR addresses a bug where plugin loading failed when plugins
imported other `BeetsPlugin` classes, namely `chroma` and `bpsync`.

- Add module path filtering to ensure only classes from the target
plugin module are considered, preventing conflicts when plugins import
other `BeetsPlugin` classes

beets/plugins.py

@@ -22,6 +22,7 @@ import re
 import sys
 from collections import defaultdict
 from functools import wraps
+from importlib import import_module
 from pathlib import Path
 from types import GenericAlias
 from typing import TYPE_CHECKING, Any, ClassVar, Literal, TypeVar
@@ -365,11 +366,11 @@ def _get_plugin(name: str) -> BeetsPlugin | None:
     """
     try:
         try:
-            namespace = __import__(f"{PLUGIN_NAMESPACE}.{name}", None, None)
+            namespace = import_module(f"{PLUGIN_NAMESPACE}.{name}")
         except Exception as exc:
             raise PluginImportError(name) from exc
 
-        for obj in getattr(namespace, name).__dict__.values():
+        for obj in namespace.__dict__.values():
             if (
                 inspect.isclass(obj)
                 and not isinstance(
@@ -378,6 +379,12 @@ def _get_plugin(name: str) -> BeetsPlugin | None:
                 and issubclass(obj, BeetsPlugin)
                 and obj != BeetsPlugin
                 and not inspect.isabstract(obj)
+                # Only consider this plugin's module or submodules to avoid
+                # conflicts when plugins import other BeetsPlugin classes
+                and (
+                    obj.__module__ == namespace.__name__
+                    or obj.__module__.startswith(f"{namespace.__name__}.")
+                )
             ):
                 return obj()
 

docs/changelog.rst

@@ -32,6 +32,8 @@ Bug fixes:
   extraartists field.
 - :doc:`plugins/spotify` Fixed an issue where candidate lookup would not find
   matches due to query escaping (single vs double quotes).
+- :doc:`plugins/chroma` :doc:`plugins/bpsync` Fix plugin loading issue caused by
+  an import of another :class:`beets.plugins.BeetsPlugin` class. :bug:`6033`
 
 For packagers:
 

test/test_logging.py

@@ -5,9 +5,10 @@ import sys
 import threading
 import unittest
 from io import StringIO
+from types import ModuleType
+from unittest.mock import patch
 
 import beets.logging as blog
-import beetsplug
 from beets import plugins, ui
 from beets.test import _common, helper
 from beets.test.helper import AsIsImporterMixin, ImportTestCase, PluginMixin
@@ -47,36 +48,46 @@ class LoggingTest(unittest.TestCase):
         assert stream.getvalue(), "foo oof baz"
 
 
+class DummyModule(ModuleType):
+    class DummyPlugin(plugins.BeetsPlugin):
+        def __init__(self):
+            plugins.BeetsPlugin.__init__(self, "dummy")
+            self.import_stages = [self.import_stage]
+            self.register_listener("dummy_event", self.listener)
+
+        def log_all(self, name):
+            self._log.debug("debug {}", name)
+            self._log.info("info {}", name)
+            self._log.warning("warning {}", name)
+
+        def commands(self):
+            cmd = ui.Subcommand("dummy")
+            cmd.func = lambda _, __, ___: self.log_all("cmd")
+            return (cmd,)
+
+        def import_stage(self, session, task):
+            self.log_all("import_stage")
+
+        def listener(self):
+            self.log_all("listener")
+
+    def __init__(self, *_, **__):
+        module_name = "beetsplug.dummy"
+        super().__init__(module_name)
+        self.DummyPlugin.__module__ = module_name
+        self.DummyPlugin = self.DummyPlugin
+
+
 class LoggingLevelTest(AsIsImporterMixin, PluginMixin, ImportTestCase):
     plugin = "dummy"
 
-    class DummyModule:
-        class DummyPlugin(plugins.BeetsPlugin):
-            def __init__(self):
-                plugins.BeetsPlugin.__init__(self, "dummy")
-                self.import_stages = [self.import_stage]
-                self.register_listener("dummy_event", self.listener)
+    @classmethod
+    def setUpClass(cls):
+        patcher = patch.dict(sys.modules, {"beetsplug.dummy": DummyModule()})
+        patcher.start()
+        cls.addClassCleanup(patcher.stop)
 
-            def log_all(self, name):
-                self._log.debug("debug {}", name)
-                self._log.info("info {}", name)
-                self._log.warning("warning {}", name)
-
-            def commands(self):
-                cmd = ui.Subcommand("dummy")
-                cmd.func = lambda _, __, ___: self.log_all("cmd")
-                return (cmd,)
-
-            def import_stage(self, session, task):
-                self.log_all("import_stage")
-
-            def listener(self):
-                self.log_all("listener")
-
-    def setUp(self):
-        sys.modules["beetsplug.dummy"] = self.DummyModule
-        beetsplug.dummy = self.DummyModule
-        super().setUp()
+        super().setUpClass()
 
     def test_command_level0(self):
         self.config["verbose"] = 0