Merge branch '362083-error-loading-mardown' into 'master'

Fix error in epic markdown preview

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/143782



Merged-by: Grzegorz Bizon <grzegorz@gitlab.com>
Approved-by: David Dieulivol <ddieulivol@gitlab.com>
Approved-by: Grzegorz Bizon <grzegorz@gitlab.com>
Reviewed-by: Grzegorz Bizon <grzegorz@gitlab.com>
Co-authored-by: Abhilash Kotte <akotte@gitlab.com>

config/routes.rb

@@ -256,8 +256,10 @@
       end
     end
 
-    resources :groups, only: [:index, :new, :create] do
-      post :preview_markdown
+    resources(:groups, only: [:index, :new, :create]) do
+      # The constraints ensure that the `group_id` parameter in the URL allows for multiple levels
+      # of subgroups, permitting both regular and encoded slashes (%2F).
+      post :preview_markdown, constraints: { group_id: %r{#{Gitlab::PathRegex.full_namespace_route_regex.source}(%2F#{Gitlab::PathRegex.full_namespace_route_regex.source})*} }
     end
 
     draw :group

ee/spec/features/epics/update_epic_spec.rb

@@ -180,6 +180,31 @@
     let(:epic) { create(:epic, group: group, description: markdown) }
 
     it_behaves_like 'updates epic'
+
+    context 'when group name has dot(.)' do
+      let_it_be(:group) { create(:group, :public, name: 'test.group') }
+      let(:epic) { create(:epic, group: group, description: markdown) }
+
+      it_behaves_like 'updates epic'
+
+      context 'when sub-group has dot(.)' do
+        let_it_be(:parent) { create(:group, :public) }
+        let_it_be(:group) { create(:group, :public, parent: parent, name: 'test.subgroup') }
+        let(:epic) { create(:epic, group: group, description: markdown) }
+
+        it_behaves_like 'updates epic'
+
+        # As we have used recurring regex in routes to have 1+ level sub groups
+        # tested 2 level subgroup here
+        context 'when 2 level subgroup name has dot(.)' do
+          let_it_be(:parent1) { create(:group, :public, parent: parent) }
+          let_it_be(:group) { create(:group, :public, parent: parent1, name: 'test.subgroup2') }
+          let(:epic) { create(:epic, group: group, description: markdown) }
+
+          it_behaves_like 'updates epic'
+        end
+      end
+    end
   end
 
   context 'when user with developer access displays the epic from a subgroup' do