Task 4: Add Services & Utilities tests (66 tests)

- test_media_utils.py: 29 tests for check_media_files, get_media_file_paths,
  has_all_images, count_video_files, has_video_files, constants
- test_nfo_factory.py: 11 tests for NFOServiceFactory.create, create_optional,
  get_nfo_factory singleton, create_nfo_service convenience
- test_series_manager_service.py: 15 tests for init, from_settings,
  process_nfo_for_series, scan_and_process_nfo, close
- test_templates_utils.py: 4 tests for TEMPLATES_DIR path resolution
- test_error_controller.py: 7 tests for 404/500 handlers (API vs HTML)

tests/unit/test_nfo_factory.py

@@ -0,0 +1,189 @@
+"""Unit tests for NFO service factory module.
+
+Tests factory instantiation, configuration precedence, singleton pattern,
+and convenience functions for creating NFOService instances.
+"""
+
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from src.core.services.nfo_factory import (
+    NFOServiceFactory,
+    create_nfo_service,
+    get_nfo_factory,
+)
+
+
+class TestNFOServiceFactoryCreate:
+    """Tests for NFOServiceFactory.create method."""
+
+    @patch("src.core.services.nfo_factory.NFOService")
+    @patch("src.core.services.nfo_factory.settings")
+    def test_create_with_explicit_api_key(self, mock_settings, mock_nfo_cls):
+        """Explicit API key takes priority over settings."""
+        mock_settings.tmdb_api_key = "settings_key"
+        mock_settings.anime_directory = "/anime"
+        mock_settings.nfo_image_size = "original"
+        mock_settings.nfo_auto_create = False
+
+        factory = NFOServiceFactory()
+        factory.create(tmdb_api_key="explicit_key")
+        mock_nfo_cls.assert_called_once_with(
+            tmdb_api_key="explicit_key",
+            anime_directory="/anime",
+            image_size="original",
+            auto_create=False,
+        )
+
+    @patch("src.core.services.nfo_factory.NFOService")
+    @patch("src.core.services.nfo_factory.settings")
+    def test_create_falls_back_to_settings(self, mock_settings, mock_nfo_cls):
+        """Falls back to settings when no explicit key provided."""
+        mock_settings.tmdb_api_key = "settings_key"
+        mock_settings.anime_directory = "/anime"
+        mock_settings.nfo_image_size = "w500"
+        mock_settings.nfo_auto_create = True
+
+        factory = NFOServiceFactory()
+        factory.create()
+        mock_nfo_cls.assert_called_once_with(
+            tmdb_api_key="settings_key",
+            anime_directory="/anime",
+            image_size="w500",
+            auto_create=True,
+        )
+
+    @patch("src.core.services.nfo_factory.settings")
+    def test_create_raises_without_api_key(self, mock_settings):
+        """Raises ValueError when no API key available from any source."""
+        mock_settings.tmdb_api_key = None
+        factory = NFOServiceFactory()
+        factory._get_api_key_from_config = MagicMock(return_value=None)
+        with pytest.raises(ValueError, match="TMDB API key not configured"):
+            factory.create()
+
+    @patch("src.core.services.nfo_factory.NFOService")
+    @patch("src.core.services.nfo_factory.settings")
+    def test_create_with_all_custom_params(self, mock_settings, mock_nfo_cls):
+        """All parameters can be overridden."""
+        mock_settings.tmdb_api_key = "default"
+        mock_settings.anime_directory = "/default"
+        mock_settings.nfo_image_size = "original"
+        mock_settings.nfo_auto_create = False
+
+        factory = NFOServiceFactory()
+        factory.create(
+            tmdb_api_key="custom",
+            anime_directory="/custom",
+            image_size="w300",
+            auto_create=True,
+        )
+        mock_nfo_cls.assert_called_once_with(
+            tmdb_api_key="custom",
+            anime_directory="/custom",
+            image_size="w300",
+            auto_create=True,
+        )
+
+    @patch("src.core.services.nfo_factory.NFOService")
+    @patch("src.core.services.nfo_factory.settings")
+    def test_create_uses_config_json_fallback(self, mock_settings, mock_nfo_cls):
+        """Falls back to config.json when settings has no key."""
+        mock_settings.tmdb_api_key = None
+        mock_settings.anime_directory = "/anime"
+        mock_settings.nfo_image_size = "original"
+        mock_settings.nfo_auto_create = False
+
+        factory = NFOServiceFactory()
+        factory._get_api_key_from_config = MagicMock(return_value="config_key")
+        factory.create()
+        mock_nfo_cls.assert_called_once()
+        call_kwargs = mock_nfo_cls.call_args[1]
+        assert call_kwargs["tmdb_api_key"] == "config_key"
+
+
+class TestNFOServiceFactoryCreateOptional:
+    """Tests for NFOServiceFactory.create_optional method."""
+
+    @patch("src.core.services.nfo_factory.settings")
+    def test_returns_none_without_api_key(self, mock_settings):
+        """Returns None instead of raising when no API key."""
+        mock_settings.tmdb_api_key = None
+        factory = NFOServiceFactory()
+        factory._get_api_key_from_config = MagicMock(return_value=None)
+        result = factory.create_optional()
+        assert result is None
+
+    @patch("src.core.services.nfo_factory.NFOService")
+    @patch("src.core.services.nfo_factory.settings")
+    def test_returns_service_when_configured(self, mock_settings, mock_nfo_cls):
+        """Returns NFOService when configuration is available."""
+        mock_settings.tmdb_api_key = "key123"
+        mock_settings.anime_directory = "/anime"
+        mock_settings.nfo_image_size = "original"
+        mock_settings.nfo_auto_create = False
+
+        factory = NFOServiceFactory()
+        result = factory.create_optional()
+        assert result is not None
+
+
+class TestGetNfoFactory:
+    """Tests for get_nfo_factory singleton function."""
+
+    def test_returns_factory_instance(self):
+        """Returns an NFOServiceFactory instance."""
+        import src.core.services.nfo_factory as mod
+        old = mod._factory_instance
+        try:
+            mod._factory_instance = None
+            factory = get_nfo_factory()
+            assert isinstance(factory, NFOServiceFactory)
+        finally:
+            mod._factory_instance = old
+
+    def test_returns_same_instance(self):
+        """Repeated calls return the same singleton."""
+        import src.core.services.nfo_factory as mod
+        old = mod._factory_instance
+        try:
+            mod._factory_instance = None
+            f1 = get_nfo_factory()
+            f2 = get_nfo_factory()
+            assert f1 is f2
+        finally:
+            mod._factory_instance = old
+
+
+class TestCreateNfoService:
+    """Tests for create_nfo_service convenience function."""
+
+    @patch("src.core.services.nfo_factory.NFOService")
+    @patch("src.core.services.nfo_factory.settings")
+    def test_convenience_function_creates_service(
+        self, mock_settings, mock_nfo_cls
+    ):
+        """Convenience function delegates to factory.create()."""
+        mock_settings.tmdb_api_key = "key"
+        mock_settings.anime_directory = "/anime"
+        mock_settings.nfo_image_size = "original"
+        mock_settings.nfo_auto_create = False
+
+        result = create_nfo_service()
+        mock_nfo_cls.assert_called_once()
+
+    @patch("src.core.services.nfo_factory.settings")
+    def test_convenience_function_raises_without_key(self, mock_settings):
+        """Convenience function raises ValueError without key."""
+        mock_settings.tmdb_api_key = None
+        import src.core.services.nfo_factory as mod
+        old = mod._factory_instance
+        try:
+            mod._factory_instance = None
+            factory = get_nfo_factory()
+            factory._get_api_key_from_config = MagicMock(return_value=None)
+            with pytest.raises(ValueError):
+                factory.create()
+        finally:
+            mod._factory_instance = old