common.postprocess_as2 bug fix for multiply valued AS2 url field

fixes https://console.cloud.google.com/errors/detail/CMOZzPLojuud_QE;time=P30D?project=bridgy-federated

common.py

@@ -391,7 +391,9 @@ def postprocess_as2(activity, user=None, target=None):
     # assert activity.get('id') or (isinstance(obj, dict) and obj.get('id'))
 
     activity['id'] = redirect_wrap(activity.get('id'))
-    activity['url'] = redirect_wrap(activity.get('url'))
+    activity['url'] = [redirect_wrap(u) for u in util.get_list(activity, 'url')]
+    if len(activity['url']) == 1:
+        activity['url'] = activity['url'][0]
 
     # copy image(s) into attachment(s). may be Mastodon-specific.
     # https://github.com/snarfed/bridgy-fed/issues/33#issuecomment-440965618

tests/test_common.py

@@ -99,6 +99,17 @@ class CommonTest(testutil.TestCase):
                 'inReplyTo': ['foo', 'bar'],
             }, user=User(id='foo.com')))
 
+    def test_postprocess_as2_multiple_url(self):
+        with app.test_request_context('/'):
+            self.assert_equals({
+                'id': 'http://localhost/r/xyz',
+                'url': ['http://localhost/r/foo', 'http://localhost/r/bar'],
+                'to': [as2.PUBLIC_AUDIENCE],
+            }, common.postprocess_as2({
+                'id': 'xyz',
+                'url': ['foo', 'bar'],
+            }, user=User(id='foo.com')))
+
     def test_postprocess_as2_actor_attributedTo(self):
         with app.test_request_context('/'):
             self.assert_equals({