Inject fake application metadata and validate it is stripped by transmogrifier

lib/pleroma/constants.ex

@@ -18,7 +18,8 @@ defmodule Pleroma.Constants do
       "emoji",
       "context_id",
       "deleted_activity_id",
-      "pleroma_internal"
+      "pleroma_internal",
+      "application"
     ]
   )
 

test/pleroma/web/activity_pub/transmogrifier_test.exs

@@ -202,7 +202,11 @@ test "it strips internal hashtag data" do
     test "it strips internal fields" do
       user = insert(:user)
 
-      {:ok, activity} = CommonAPI.post(user, %{status: "#2hu :firefox:"})
+      {:ok, activity} =
+        CommonAPI.post(user, %{
+          status: "#2hu :firefox:",
+          application: %{name: "TestClient", website: "https://pleroma.social"}
+        })
 
       {:ok, modified} = Transmogrifier.prepare_outgoing(activity.data)
 
@@ -213,6 +217,7 @@ test "it strips internal fields" do
       assert is_nil(modified["object"]["announcements"])
       assert is_nil(modified["object"]["announcement_count"])
       assert is_nil(modified["object"]["context_id"])
+      assert is_nil(modified["object"]["application"])
     end
 
     test "it strips internal fields of article" do