diff --git a/modules/costs/spec/factories/journal/time_entry_journal_factory.rb b/modules/costs/spec/factories/journal/time_entry_journal_factory.rb
index af78e1d5a27..3f028d05e73 100644
--- a/modules/costs/spec/factories/journal/time_entry_journal_factory.rb
+++ b/modules/costs/spec/factories/journal/time_entry_journal_factory.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 #-- copyright
 # OpenProject is an open source project management software.
 # Copyright (C) the OpenProject GmbH
@@ -27,6 +29,5 @@
 #++
 
 FactoryBot.define do
-  factory :journal_time_entry_journal, class: "Journal::TimeEntryJournal" do
-  end
+  factory :journal_time_entry_journal, class: "Journal::TimeEntryJournal"
 end
diff --git a/spec/factories/journal_factory.rb b/spec/factories/journal_factory.rb
index 200480577c1..f9f2718a074 100644
--- a/spec/factories/journal_factory.rb
+++ b/spec/factories/journal_factory.rb
@@ -68,21 +68,37 @@ FactoryBot.define do
     factory :message_journal, class: "Journal" do
       journable_type { "Message" }
       data { build(:journal_message_journal) }
+
+      callback(:after_stub) do |journal, options|
+        journal.journable ||= options.journable || build_stubbed(:message)
+      end
     end
 
     factory :news_journal, class: "Journal" do
       journable_type { "News" }
       data { build(:journal_message_journal) }
+
+      callback(:after_stub) do |journal, options|
+        journal.journable ||= options.journable || build_stubbed(:news)
+      end
     end
 
     factory :project_journal, class: "Journal" do
       journable factory: :project
       data { build(:journal_project_journal) }
+
+      callback(:after_stub) do |journal, options|
+        journal.journable ||= options.journable || build_stubbed(:project)
+      end
     end
 
     factory :time_entry_journal, class: "Journal" do
       journable_type { "TimeEntry" }
       data { association(:journal_time_entry_journal) }
+
+      callback(:after_stub) do |journal, options|
+        journal.journable ||= options.journable || build_stubbed(:time_entry)
+      end
     end
   end
 end
diff --git a/spec/lib/open_project/journal_formatter/polymorphic_association_spec.rb b/spec/lib/open_project/journal_formatter/polymorphic_association_spec.rb
new file mode 100644
index 00000000000..41b5b615e6d
--- /dev/null
+++ b/spec/lib/open_project/journal_formatter/polymorphic_association_spec.rb
@@ -0,0 +1,93 @@
+# frozen_string_literal: true
+
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require "spec_helper"
+
+RSpec.describe JournalFormatter::PolymorphicAssociation do
+  describe ".render" do
+    let(:journal) { build_stubbed(:time_entry_journal) }
+    let(:instance) { described_class.new(journal) }
+
+    let(:old_wp) { create(:work_package) }
+    let(:new_wp) { create(:work_package) }
+    let(:old_value) { old_wp&.to_gid }
+    let(:new_value) { new_wp&.to_gid }
+
+    context "when setting new value" do
+      let(:old_wp) { nil }
+
+      it "renders the new value" do
+        expect(instance.render("entity_gid", [old_value, new_value]))
+          .to eq(I18n.t(:text_journal_set_to,
+                        label: "<strong>Logged for</strong>",
+                        value: "<i>#{new_wp.subject}</i>"))
+
+        expect(instance.render("entity_gid", [old_value, new_value], html: false))
+          .to eq(I18n.t(:text_journal_set_to,
+                        label: "Logged for",
+                        value: new_wp.subject))
+      end
+    end
+
+    context "when changing value" do
+      it "renders the change from old to new value" do
+        expect(instance.render("entity_gid", [old_value, new_value]))
+          .to eq(I18n.t(:text_journal_changed_plain,
+                        label: "<strong>Logged for</strong>",
+                        linebreak: nil,
+                        old: "<i>#{old_wp.subject}</i>",
+                        new: "<i>#{new_wp.subject}</i>"))
+
+        expect(instance.render("entity_gid", [old_value, new_value], html: false))
+          .to eq(I18n.t(:text_journal_changed_plain,
+                        label: "Logged for",
+                        linebreak: nil,
+                        old: old_wp.subject,
+                        new: new_wp.subject))
+      end
+    end
+
+    context "when removing the value" do
+      let(:new_value) { nil }
+
+      it "renders as removed" do
+        expect(instance.render("entity_gid", [old_value, new_value]))
+          .to eq(I18n.t(:text_journal_deleted,
+                        label: "<strong>Logged for</strong>",
+                        old: "<strike><i>#{old_wp.subject}</i></strike>"))
+
+        expect(instance.render("entity_gid", [old_value, new_value], html: false))
+          .to eq(I18n.t(:text_journal_deleted,
+                        label: "Logged for",
+                        old: old_wp.subject))
+      end
+    end
+  end
+end