fixed User.unfollow with synchronization external user

lib/pleroma/user.ex

@@ -742,6 +742,7 @@ defmodule Pleroma.User do
     |> update_and_set_cache()
   end
 
+  @spec maybe_fetch_follow_information(User.t()) :: User.t()
   def maybe_fetch_follow_information(user) do
     with {:ok, user} <- fetch_follow_information(user) do
       user
@@ -799,9 +800,10 @@ defmodule Pleroma.User do
     end
   end
 
+  @spec maybe_update_following_count(User.t()) :: User.t()
   def maybe_update_following_count(%User{local: false} = user) do
     if Pleroma.Config.get([:instance, :external_user_synchronization]) do
-      {:ok, maybe_fetch_follow_information(user)}
+      maybe_fetch_follow_information(user)
     else
       user
     end

test/user_test.exs

@@ -192,6 +192,45 @@ defmodule Pleroma.UserTest do
   #   assert websub
   # end
 
+  describe "unfollow/2" do
+    setup do
+      setting = Pleroma.Config.get([:instance, :external_user_synchronization])
+
+      on_exit(fn ->
+        Pleroma.Config.put([:instance, :external_user_synchronization], setting)
+      end)
+
+      :ok
+    end
+
+    test "unfollow with syncronizes external user" do
+      Pleroma.Config.put([:instance, :external_user_synchronization], true)
+
+      followed =
+        insert(:user,
+          nickname: "fuser1",
+          follower_address: "http://localhost:4001/users/fuser1/followers",
+          following_address: "http://localhost:4001/users/fuser1/following",
+          ap_id: "http://localhost:4001/users/fuser1"
+        )
+
+      user =
+        insert(:user, %{
+          local: false,
+          nickname: "fuser2",
+          ap_id: "http://localhost:4001/users/fuser2",
+          follower_address: "http://localhost:4001/users/fuser2/followers",
+          following_address: "http://localhost:4001/users/fuser2/following",
+          following: [User.ap_followers(followed)]
+        })
+
+      {:ok, user, _activity} = User.unfollow(user, followed)
+
+      user = User.get_cached_by_id(user.id)
+
+      assert user.following == []
+    end
+
     test "unfollow takes a user and another user" do
       followed = insert(:user)
       user = insert(:user, %{following: [User.ap_followers(followed)]})
@@ -211,6 +250,7 @@ defmodule Pleroma.UserTest do
       user = User.get_cached_by_id(user.id)
       assert user.following == [user.ap_id]
     end
+  end
 
   test "test if a user is following another user" do
     followed = insert(:user)