FIX: Show topic titles in deleted-posts (#19610)

Show topic titles in deleted-posts

spec/serializers/admin_user_action_serializer_spec.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+describe AdminUserActionSerializer do
+  fab!(:user) { Fabricate(:user) }
+  fab!(:admin) { Fabricate(:admin) }
+  let(:guardian) { Guardian.new(admin) }
+
+  fab!(:topic) { Fabricate(:topic) }
+  fab!(:post) { Fabricate(:post, topic: topic) }
+
+  it "includes the slug/title/category ID for a post's deleted topic" do
+    topic.trash!
+
+    json = AdminUserActionSerializer.new(post, scope: guardian, root: false).as_json
+
+    expect(json[:slug]).to eq(topic.slug)
+    expect(json[:title]).to eq(topic.title)
+    expect(json[:category_id]).to eq(topic.category_id)
+  end
+end