Public getting stripped from unlisted activity CC: Add possible tests

test/fixtures/poast_unlisted.json

@@ -0,0 +1,65 @@
+{
+   "@context" : [
+      "https://www.w3.org/ns/activitystreams",
+      "https://poa.st/schemas/litepub-0.1.jsonld",
+      {
+         "@language" : "und"
+      }
+   ],
+   "actor" : "https://poa.st/users/TrevorGoodchild",
+   "attachment" : [],
+   "attributedTo" : "https://poa.st/users/TrevorGoodchild",
+   "cc" : [
+      "https://www.w3.org/ns/activitystreams#Public"
+   ],
+   "context" : "https://poa.st/contexts/c6d125f1-4e7f-43bd-aa31-33de4d90d049",
+   "conversation" : "https://poa.st/contexts/c6d125f1-4e7f-43bd-aa31-33de4d90d049",
+   "directMessage" : false,
+   "id" : "https://poa.st/activities/bbd3347a-4a89-4cdb-bf86-4f9eed9506e3",
+   "object" : {
+      "actor" : "https://poa.st/users/TrevorGoodchild",
+      "attachment" : [],
+      "attributedTo" : "https://poa.st/users/TrevorGoodchild",
+      "cc" : [
+         "https://www.w3.org/ns/activitystreams#Public"
+      ],
+      "content" : "<span class=\"recipients-inline\"><span class=\"h-card\"><a class=\"u-url mention\" data-user=\"AfOKoodAGeklO08nyq\" href=\"https://poa.st/users/HoroTheWhiteWolf\" rel=\"ugc\">@<span>HoroTheWhiteWolf</span></a></span> </span>&gt;please let this be his zero fucks given final statement before he joins the 52%+ tranny club",
+      "context" : "https://poa.st/contexts/c6d125f1-4e7f-43bd-aa31-33de4d90d049",
+      "conversation" : "https://poa.st/contexts/c6d125f1-4e7f-43bd-aa31-33de4d90d049",
+      "id" : "https://poa.st/objects/7eb785d5-a556-4070-9091-f4afb226466c",
+      "inReplyTo" : "https://poa.st/objects/71995b41-cfb2-48ce-abce-76d570d54edc",
+      "published" : "2025-05-03T23:54:07.489885Z",
+      "repliesCount" : 2,
+      "sensitive" : false,
+      "source" : {
+         "content" : ">please let this be his zero fucks given final statement before he joins the 52%+ tranny club",
+         "mediaType" : "text/plain"
+      },
+      "summary" : "",
+      "tag" : [
+         {
+            "href" : "https://poa.st/users/HoroTheWhiteWolf",
+            "name" : "@HoroTheWhiteWolf",
+            "type" : "Mention"
+         }
+      ],
+      "to" : [
+         "https://poa.st/users/HoroTheWhiteWolf",
+         "https://poa.st/users/TrevorGoodchild/followers"
+      ],
+      "type" : "Note"
+   },
+   "published" : "2025-05-03T23:54:07.489837Z",
+   "tag" : [
+      {
+         "href" : "https://poa.st/users/HoroTheWhiteWolf",
+         "name" : "@HoroTheWhiteWolf",
+         "type" : "Mention"
+      }
+   ],
+   "to" : [
+      "https://poa.st/users/HoroTheWhiteWolf",
+      "https://poa.st/users/TrevorGoodchild/followers"
+   ],
+   "type" : "Create"
+}

test/pleroma/web/activity_pub/transmogrifier/note_handling_test.exs

@@ -786,4 +786,35 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier.NoteHandlingTest do
     assert object.data["context"] == object.data["inReplyTo"]
     assert modified.data["context"] == object.data["inReplyTo"]
   end
+
+  test "it keeps the public address in cc in the activity when it is present" do
+    data =
+      File.read!("test/fixtures/mastodon-post-activity.json")
+      |> Jason.decode!()
+
+    object =
+      data["object"]
+      |> Map.put("cc", ["https://www.w3.org/ns/activitystreams#Public"])
+      |> Map.put("to", [])
+
+    data =
+      data
+      |> Map.put("object", object)
+      |> Map.put("cc", ["https://www.w3.org/ns/activitystreams#Public"])
+      |> Map.put("to", [])
+
+    {:ok, %Activity{} = modified} = Transmogrifier.handle_incoming(data)
+    assert modified.data["cc"] == ["https://www.w3.org/ns/activitystreams#Public"]
+  end
+
+  test "it tries it with the real poast_unlisted.json, ensuring that public is in the cc" do
+    data =
+      File.read!("test/fixtures/poast_unlisted.json")
+      |> Jason.decode!()
+
+    _user = insert(:user, ap_id: data["actor"])
+
+    {:ok, %Activity{} = modified} = Transmogrifier.handle_incoming(data)
+    assert modified.data["cc"] == ["https://www.w3.org/ns/activitystreams#Public"]
+  end
 end

test/pleroma/web/activity_pub/transmogrifier_test.exs

@@ -757,6 +757,43 @@ defmodule Pleroma.Web.ActivityPub.TransmogrifierTest do
       refute recipient.follower_address in fixed_object["cc"]
       refute recipient.follower_address in fixed_object["to"]
     end
+
+    test "preserves public URL in cc even when not explicitly mentioned", %{user: user} do
+      public_url = "https://www.w3.org/ns/activitystreams#Public"
+
+      # Case 1: Public URL in cc but no mentions
+      object = %{
+        "actor" => user.ap_id,
+        "to" => ["https://social.beepboop.ga/users/dirb"],
+        "cc" => [public_url],
+        "tag" => []
+      }
+
+      fixed_object = Transmogrifier.fix_explicit_addressing(object, user.follower_address)
+      assert public_url in fixed_object["cc"]
+
+      # Case 2: Public URL in cc, with mentions but public not in to
+      object = %{
+        "actor" => user.ap_id,
+        "to" => ["https://pleroma.gold/users/user1"],
+        "cc" => [public_url],
+        "tag" => [%{"type" => "Mention", "href" => "https://pleroma.gold/users/user1"}]
+      }
+
+      fixed_object = Transmogrifier.fix_explicit_addressing(object, user.follower_address)
+      assert public_url in fixed_object["cc"]
+
+      # Case 3: Public URL in to, it should be moved to to
+      object = %{
+        "actor" => user.ap_id,
+        "to" => [public_url],
+        "cc" => [],
+        "tag" => []
+      }
+
+      fixed_object = Transmogrifier.fix_explicit_addressing(object, user.follower_address)
+      assert public_url in fixed_object["to"]
+    end
   end
 
   describe "fix_summary/1" do