Test more types we do not want to receive from strangers

test/pleroma/web/activity_pub/activity_pub_controller_test.exs

@@ -688,10 +688,13 @@ test "without valid signature, " <>
     # we capture all the params and process it later in the Oban job.
     # Once we begin processing it through Oban we risk fetching the actor to validate the
     # activity which just leads to inserting a new user to process a Delete not relevant to us.
-    test "Deletes from an unknown actor are discarded", %{conn: conn} do
+    test "Activities of certain types from an unknown actor are discarded", %{conn: conn} do
+      example_bad_types = ["Announce", "Delete", "Undo"]
+
+      Enum.each(example_bad_types, fn bad_type ->
         params =
           %{
-          "type" => "Delete",
+            "type" => bad_type,
             "actor" => "https://unknown.mastodon.instance/users/somebody"
           }
           |> Jason.encode!()
@@ -703,6 +706,7 @@ test "Deletes from an unknown actor are discarded", %{conn: conn} do
         |> json_response(400)
 
         assert all_enqueued() == []
+      end)
     end
 
     test "accepts Add/Remove activities", %{conn: conn} do