activitypub: publisher: align sharedinbox usage with AP specification rules

While debugging the follow breakage, I observed that our sharedInbox usage
did not match the rules in the specification.  Accordingly, I have better
aligned our usage of sharedInbox with the rules outlined in the ActivityPub
specification.

1 files changed, 112 insertions, 0 deletions

diff --git a/test/web/activity_pub/publisher_test.exs b/test/web/activity_pub/publisher_test.exs
new file mode 100644
index 000000000..2b15b3edc
--- /dev/null
+++ b/test/web/activity_pub/publisher_test.exs
@@ -0,0 +1,112 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.PublisherTest do
+  use Pleroma.DataCase
+
+  import Pleroma.Factory
+
+  alias Pleroma.Activity
+  alias Pleroma.Web.ActivityPub.Publisher
+
+  @as_public "https://www.w3.org/ns/activitystreams#Public"
+
+  describe "determine_inbox/2" do
+    test "it returns sharedInbox for messages involving as:Public in to" do
+      user =
+        insert(:user, %{
+          info: %{source_data: %{"endpoints" => %{"sharedInbox" => "http://example.com/inbox"}}}
+        })
+
+      activity = %Activity{
+        data: %{"to" => [@as_public], "cc" => [user.follower_address]}
+      }
+
+      assert Publisher.determine_inbox(activity, user) == "http://example.com/inbox"
+    end
+
+    test "it returns sharedInbox for messages involving as:Public in cc" do
+      user =
+        insert(:user, %{
+          info: %{source_data: %{"endpoints" => %{"sharedInbox" => "http://example.com/inbox"}}}
+        })
+
+      activity = %Activity{
+        data: %{"cc" => [@as_public], "to" => [user.follower_address]}
+      }
+
+      assert Publisher.determine_inbox(activity, user) == "http://example.com/inbox"
+    end
+
+    test "it returns sharedInbox for messages involving multiple recipients in to" do
+      user =
+        insert(:user, %{
+          info: %{source_data: %{"endpoints" => %{"sharedInbox" => "http://example.com/inbox"}}}
+        })
+
+      user_two = insert(:user)
+      user_three = insert(:user)
+
+      activity = %Activity{
+        data: %{"cc" => [], "to" => [user.ap_id, user_two.ap_id, user_three.ap_id]}
+      }
+
+      assert Publisher.determine_inbox(activity, user) == "http://example.com/inbox"
+    end
+
+    test "it returns sharedInbox for messages involving multiple recipients in cc" do
+      user =
+        insert(:user, %{
+          info: %{source_data: %{"endpoints" => %{"sharedInbox" => "http://example.com/inbox"}}}
+        })
+
+      user_two = insert(:user)
+      user_three = insert(:user)
+
+      activity = %Activity{
+        data: %{"to" => [], "cc" => [user.ap_id, user_two.ap_id, user_three.ap_id]}
+      }
+
+      assert Publisher.determine_inbox(activity, user) == "http://example.com/inbox"
+    end
+
+    test "it returns sharedInbox for messages involving multiple recipients in total" do
+      user =
+        insert(:user, %{
+          info: %{
+            source_data: %{
+              "inbox" => "http://example.com/personal-inbox",
+              "endpoints" => %{"sharedInbox" => "http://example.com/inbox"}
+            }
+          }
+        })
+
+      user_two = insert(:user)
+
+      activity = %Activity{
+        data: %{"to" => [user_two.ap_id], "cc" => [user.ap_id]}
+      }
+
+      assert Publisher.determine_inbox(activity, user) == "http://example.com/inbox"
+    end
+
+    test "it returns inbox for messages involving single recipients in total" do
+      user =
+        insert(:user, %{
+          info: %{
+            source_data: %{
+              "inbox" => "http://example.com/personal-inbox",
+              "endpoints" => %{"sharedInbox" => "http://example.com/inbox"}
+            }
+          }
+        })
+
+      activity = %Activity{
+        data: %{"to" => [user.ap_id], "cc" => []}
+      }
+
+      assert Publisher.determine_inbox(activity, user) == "http://example.com/personal-inbox"
+    end
+  end
+end