lib/pleroma/user_note.ex

@@ -31,7 +31,7 @@ def show(%User{} = source, %User{} = target) do
            UserNote
            |> where(source_id: ^source.id, target_id: ^target.id)
            |> Repo.one() do
-      note.comment
+      note.comment || ""
     else
       _ -> ""
     end

test/pleroma/user_note_test.exs

@@ -0,0 +1,39 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.UserNoteTest do
+  alias Pleroma.UserNote
+
+  use Pleroma.DataCase, async: false
+  import Pleroma.Factory
+
+  describe "show/2" do
+    setup do
+      {:ok, users: insert_list(2, :user)}
+    end
+
+    test "if record does not exist, returns empty string", %{users: [user1, user2]} do
+      comment = UserNote.show(user1, user2)
+
+      assert comment == ""
+    end
+
+    test "if record exists with comment == nil, returns empty string", %{users: [user1, user2]} do
+      UserNote.create(user1, user2, nil)
+
+      comment = UserNote.show(user1, user2)
+
+      assert comment == ""
+    end
+
+    test "if record exists with non-nil comment, returns comment", %{users: [user1, user2]} do
+      expected_comment = "hello"
+      UserNote.create(user1, user2, expected_comment)
+
+      comment = UserNote.show(user1, user2)
+
+      assert comment == expected_comment
+    end
+  end
+end