Fix component exporting for Addon base class

scrapy/addons/__init__.py

@@ -84,7 +84,7 @@ class Addon(object):
                 # e.g. for DOWNLOADER_MIDDLEWARES: {'myclass': 100}
                 k = comp
                 v = config.get('order', self.component_order)
-            settings.set(self.component_type, {k: v}, 'addon')
+            settings[self.component_type].update({k: v}, 'addon')
 
     def export_basics(self, settings):
         """Export the :attr:`basic_settings` attribute into the settings object.

tests/test_addons/__init__.py

@@ -38,7 +38,9 @@ class AddonTest(unittest.TestCase):
         verifyObject(IAddon, self.testaddon)
 
     def test_export_component(self):
-        settings = BaseSettings({'ITEM_PIPELINES': {}}, 'default')
+        settings = BaseSettings({'ITEM_PIPELINES': BaseSettings(),
+                                 'DOWNLOAD_HANDLERS': BaseSettings()},
+                                'default')
         self.testaddon.component_type = None
         self.testaddon.export_component({}, settings)
         self.assertEqual(len(settings['ITEM_PIPELINES']), 0)