Fix displaying roadmap for epics without dates

- includes pdated translations

ee/app/assets/javascripts/roadmap/mixins/common_mixin.js

@@ -75,7 +75,9 @@ export default {
       };
     },
     timeframeString(roadmapItem) {
-      if (roadmapItem.startDateUndefined) {
+      if (roadmapItem.startDateUndefined && roadmapItem.endDateUndefined) {
+        return sprintf(s__('GroupRoadmap|No start and end date'));
+      } else if (roadmapItem.startDateUndefined) {
         return sprintf(s__('GroupRoadmap|No start date – %{dateWord}'), {
           dateWord: dateInWords(this.endDate, true),
         });

ee/changelogs/unreleased/214026-fix-roadmap-date-display.yml

+---
+title: Display correct information on Roadmap when an epic has no start and due date
+merge_request: 37093
+author:
+type: fixed

ee/spec/frontend/roadmap/components/epic_item_spec.js

@@ -103,6 +103,13 @@ describe('EpicItemComponent', () => {
       expect(wrapper.vm.timeframeString(mockEpic)).toBe('Jul 10, 2017 – Jun 2, 2018');
     });
 
+    it('returns timeframe string correctly when no dates are defined', () => {
+      const epic = { ...mockEpic, endDateUndefined: true, startDateUndefined: true };
+      wrapper = createComponent({ epic });
+
+      expect(wrapper.vm.timeframeString(epic)).toBe('No start and end date');
+    });
+
     it('returns timeframe string correctly when only start date is defined', () => {
       const epic = { ...mockEpic, endDateUndefined: true };
       wrapper = createComponent({ epic });

locale/gitlab.pot

@@ -11653,6 +11653,9 @@ msgstr ""
 msgid "GroupRoadmap|%{startDateInWords} – %{endDateInWords}"
 msgstr ""
 
+msgid "GroupRoadmap|No start and end date"
+msgstr ""
+
 msgid "GroupRoadmap|No start date – %{dateWord}"
 msgstr ""