Fixes #5168 - Ticket history shows html when updating articles.

Co-authored-by: Florian Liebe <fl@zammad.com>

app/assets/javascripts/app/controllers/_application_controller/_modal_generic_history.coffee

@@ -51,6 +51,9 @@ class App.GenericHistory extends App.ControllerModal
     for item in items
       if item.object is 'Ticket::Article'
         item.object = 'Article'
+        if item.attribute is 'body'
+          item.value_from = App.Utils.html2text(item.value_from)
+          item.value_to   = App.Utils.html2text(item.value_to)
       if item.object is 'Ticket::SharedDraftZoom'
         item.object = 'Draft'
 

spec/system/ticket/zoom/history_spec.rb

@@ -24,4 +24,29 @@ def authenticate
       expect(page).to have_text('triggered')
     end
   end
+
+  describe 'Ticket history shows html when updating articles #5168' do
+    let(:old_body) { SecureRandom.uuid }
+    let(:new_body) { SecureRandom.uuid }
+    let(:ticket)   { create(:ticket, group: Group.first) }
+    let(:article)  { create(:ticket_article, ticket: ticket, body: "<div><b>#{old_body}</b></div>", content_type: 'text/html') }
+
+    def authenticate
+      article.update(body: "<div><b>#{new_body}</b></div>")
+      true
+    end
+
+    before do
+      visit "#ticket/zoom/#{ticket.id}"
+    end
+
+    it 'does not show html in the ticket history', :aggregate_failures do
+      click '.sidebar-header-headline'
+      click 'li[data-type=ticket-history]'
+      expect(page).to have_text(old_body)
+      expect(page).to have_text(new_body)
+      expect(page).to have_no_text('<div>')
+      expect(page).to have_no_text('</div>')
+    end
+  end
 end