Remove unused feature flag

Removes feature flag `:roadmap_buffered_rendering`
as the buffered rendering for Roadmap is broken
for a while so we no longer need it.

changelogs/unreleased/kp-remove-roadmap-buffered-rendering-ff.yml

+---
+title: Remove unused feature flag ':roadmap_buffered_rendering'
+merge_request: 57486
+author:
+type: removed

ee/app/assets/javascripts/roadmap/components/epics_list_section.vue

 <script>
-import VirtualList from 'vue-virtual-scroll-list';
 import { mapState, mapActions } from 'vuex';
 import glFeatureFlagsMixin from '~/vue_shared/mixins/gl_feature_flags_mixin';
 
@@ -14,7 +13,6 @@ export default {
   EpicItem,
   epicItemHeight: EPIC_ITEM_HEIGHT,
   components: {
-    VirtualList,
     EpicItem,
     CurrentDayIndicator,
   },
@@ -140,22 +138,6 @@ export default {
     handleEpicsListScroll({ scrollTop, clientHeight, scrollHeight }) {
       this.showBottomShadow = Math.ceil(scrollTop) + clientHeight < scrollHeight;
     },
-    getEpicItemProps(index) {
-      return {
-        key: generateKey(this.displayedEpics[index]),
-        props: {
-          epic: this.displayedEpics[index],
-          presetType: this.presetType,
-          timeframe: this.timeframe,
-          currentGroupId: this.currentGroupId,
-          clientWidth: this.clientWidth,
-          childLevel: 0,
-          childrenEpics: this.childrenEpics,
-          childrenFlags: this.childrenFlags,
-          hasFiltersApplied: this.hasFiltersApplied,
-        },
-      };
-    },
     toggleIsEpicExpanded(epic) {
       this.toggleEpic({ parentItem: epic });
     },
@@ -166,34 +148,20 @@ export default {
 
 <template>
   <div :style="sectionContainerStyles" class="epics-list-section">
-    <template v-if="glFeatures.roadmapBufferedRendering && !emptyRowContainerVisible">
-      <virtual-list
-        v-if="displayedEpics.length"
-        :size="$options.epicItemHeight"
-        :remain="bufferSize"
-        :bench="bufferSize"
-        :scrollelement="roadmapShellEl"
-        :item="$options.EpicItem"
-        :itemcount="displayedEpics.length"
-        :itemprops="getEpicItemProps"
-      />
-    </template>
-    <template v-else>
-      <epic-item
-        v-for="epic in displayedEpics"
-        ref="epicItems"
-        :key="generateKey(epic)"
-        :preset-type="presetType"
-        :epic="epic"
-        :timeframe="timeframe"
-        :current-group-id="currentGroupId"
-        :client-width="clientWidth"
-        :child-level="0"
-        :children-epics="childrenEpics"
-        :children-flags="childrenFlags"
-        :has-filters-applied="hasFiltersApplied"
-      />
-    </template>
+    <epic-item
+      v-for="epic in displayedEpics"
+      ref="epicItems"
+      :key="generateKey(epic)"
+      :preset-type="presetType"
+      :epic="epic"
+      :timeframe="timeframe"
+      :current-group-id="currentGroupId"
+      :client-width="clientWidth"
+      :child-level="0"
+      :children-epics="childrenEpics"
+      :children-flags="childrenFlags"
+      :has-filters-applied="hasFiltersApplied"
+    />
     <div
       v-if="emptyRowContainerVisible"
       :style="emptyRowContainerStyles"

ee/app/controllers/groups/roadmap_controller.rb

@@ -8,7 +8,6 @@ module Groups
     before_action :check_epics_available!
     before_action :persist_roadmap_layout, only: [:show]
     before_action do
-      push_frontend_feature_flag(:roadmap_buffered_rendering, @group)
       push_frontend_feature_flag(:async_filtering, @group, default_enabled: true)
     end
 

ee/config/feature_flags/development/roadmap_buffered_rendering.yml

----
-name: roadmap_buffered_rendering
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/19875
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/216792
-milestone: '12.6'
-type: development
-group: group::product planning
-default_enabled: false

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

 import { shallowMount, createLocalVue } from '@vue/test-utils';
-import VirtualList from 'vue-virtual-scroll-list';
 import EpicItem from 'ee/roadmap/components/epic_item.vue';
 import EpicsListSection from 'ee/roadmap/components/epics_list_section.vue';
 import {
@@ -44,7 +43,6 @@ const createComponent = ({
   timeframe = mockTimeframeMonths,
   currentGroupId = mockGroupId,
   presetType = PRESET_TYPES.MONTHS,
-  roadmapBufferedRendering = true,
   hasFiltersApplied = false,
 } = {}) => {
   return shallowMount(EpicsListSection, {
@@ -61,9 +59,6 @@ const createComponent = ({
       currentGroupId,
       hasFiltersApplied,
     },
-    provide: {
-      glFeatures: { roadmapBufferedRendering },
-    },
   });
 };
 
@@ -234,34 +229,6 @@ describe('EpicsListSectionComponent', () => {
         expect(wrapper.vm.showBottomShadow).toBe(false);
       });
     });
-
-    describe('getEpicItemProps', () => {
-      it('returns an object containing props for EpicItem component', () => {
-        expect(wrapper.vm.getEpicItemProps(1)).toEqual(
-          expect.objectContaining({
-            key: `epic-${wrapper.vm.epics[1].id}`,
-            props: {
-              epic: wrapper.vm.epics[1],
-              presetType: wrapper.vm.presetType,
-              timeframe: wrapper.vm.timeframe,
-              currentGroupId: wrapper.vm.currentGroupId,
-              clientWidth: wrapper.vm.clientWidth,
-              childLevel: 0,
-              childrenEpics: expect.objectContaining({
-                41: expect.arrayContaining([mockFormattedChildEpic1]),
-              }),
-              childrenFlags: expect.objectContaining({
-                1: {
-                  itemChildrenFetchInProgress: false,
-                  itemExpanded: false,
-                },
-              }),
-              hasFiltersApplied: false,
-            },
-          }),
-        );
-      });
-    });
   });
 
   describe('template', () => {
@@ -269,30 +236,7 @@ describe('EpicsListSectionComponent', () => {
       expect(wrapper.classes('epics-list-section')).toBe(true);
     });
 
-    it('renders virtual-list when roadmapBufferedRendering is `true` and `epics.length` is more than `bufferSize`', () => {
-      wrapper.vm.setBufferSize(5);
-
-      return wrapper.vm.$nextTick(() => {
-        expect(wrapper.find(VirtualList).exists()).toBe(true);
-      });
-    });
-
-    it('renders epic-item when roadmapBufferedRendering is `false`', () => {
-      // Destroy the wrapper created in the beforeEach above
-      wrapper.destroy();
-
-      const wrapperFlagOff = createComponent({
-        roadmapBufferedRendering: false,
-      });
-
-      expect(wrapperFlagOff.find(EpicItem).exists()).toBe(true);
-
-      wrapperFlagOff.destroy();
-    });
-
-    it('renders epic-item when roadmapBufferedRendering is `true` and `epics.length` is less than `bufferSize`', () => {
-      wrapper.vm.setBufferSize(50);
-
+    it('renders epic-item', () => {
       expect(wrapper.find(EpicItem).exists()).toBe(true);
     });