test: add importer test for fetchart plugin

Test whether fetchart is run during the import phase and, specifically,
whether the `fetch_for_asis` setting is honored. Mock boundary is
between `FetchArtPlugin` and `ArtSource`, an already-existing internal
API boundary.

beetsplug/fetchart.py

@@ -1439,6 +1439,10 @@ class FetchArtPlugin(plugins.BeetsPlugin, RequestMixin):
         except UnknownPairError as e:
             raise UserError(e)
 
+    @cached_property
+    def fetch_for_asis(self) -> bool:
+        return self.config["fetch_for_asis"].get(bool)
+
     @staticmethod
     def _is_source_file_removal_enabled() -> bool:
         return config["import"]["delete"].get(bool) or config["import"][
@@ -1467,7 +1471,7 @@ class FetchArtPlugin(plugins.BeetsPlugin, RequestMixin):
             if task.choice_flag == importer.Action.ASIS:
                 # For as-is imports, don't search Web sources for art,
                 # unless fetch_for_asis is set
-                local = not self.config["fetch_for_asis"]
+                local = not self.fetch_for_asis
             elif task.choice_flag in (
                 importer.Action.APPLY,
                 importer.Action.RETAG,

test/plugins/test_fetchart.py

@@ -1,11 +1,66 @@
 import ctypes
 import os
 import sys
+from typing import Any, ClassVar
 from unittest import mock
 
-from beets import util
-from beets.test.helper import IOMixin, PluginTestHelper
-from beetsplug.fetchart import FetchArtPlugin, FileSystem
+from beets import importer, util
+from beets.test.helper import (
+    AutotagImportHelper,
+    IOMixin,
+    PluginMixin,
+    PluginTestHelper,
+)
+from beetsplug.fetchart import CoverArtArchive, FetchArtPlugin, FileSystem
+
+
+class TestFetchartImport(PluginMixin, AutotagImportHelper):
+    plugin = "fetchart"
+    preload_plugin = False
+    plugin_defaults: ClassVar[Any] = {"sources": ["filesystem", "coverart"]}
+
+    def setup_beets(self):
+        super().setup_beets()
+
+        self.prepare_album_for_import(1)
+        self.setup_importer()
+
+        self.local_art_patcher = mock.patch.object(
+            FileSystem, "get", autospec=True, return_value=iter(())
+        )
+        self.local_art_mock = self.local_art_patcher.start()
+        self.remote_art_patcher = mock.patch.object(
+            CoverArtArchive, "get", autospec=True, return_value=iter(())
+        )
+        self.remote_art_mock = self.remote_art_patcher.start()
+
+    def teardown_beets(self):
+        super().teardown_beets()
+        self.local_art_patcher.stop()
+        self.remote_art_patcher.stop()
+
+    def test_asis_skips_network_sources(self):
+        self.importer.add_choice(importer.Action.ASIS)
+        with self.configure_plugin(self.plugin_defaults):
+            self.importer.run()
+        self.local_art_mock.assert_called()
+        self.remote_art_mock.assert_not_called()
+
+    def test_apply_uses_network_sources(self):
+        self.importer.add_choice(importer.Action.APPLY)
+        with self.configure_plugin(self.plugin_defaults):
+            self.importer.run()
+        self.local_art_mock.assert_called()
+        self.remote_art_mock.assert_called()
+
+    def test_fetch_for_asis_uses_network_sources(self):
+        self.importer.add_choice(importer.Action.ASIS)
+        with self.configure_plugin(
+            self.plugin_defaults | {"fetch_for_asis": True}
+        ):
+            self.importer.run()
+        self.local_art_mock.assert_called()
+        self.remote_art_mock.assert_called()
 
 
 class TestFetchartCli(IOMixin, PluginTestHelper):