Add event description for selected stage in VSA

- This MR adds stage info popovers
to path navigation displaying
start and end event description

ee/app/assets/javascripts/analytics/cycle_analytics/components/path_navigation.vue

 <script>
-import { GlPath, GlDeprecatedSkeletonLoading as GlSkeletonLoading } from '@gitlab/ui';
+import {
+  GlPath,
+  GlPopover,
+  GlDeprecatedSkeletonLoading as GlSkeletonLoading,
+  GlSafeHtmlDirective as SafeHtml,
+} from '@gitlab/ui';
 
 export default {
   name: 'PathNavigation',
   components: {
     GlPath,
     GlSkeletonLoading,
+    GlPopover,
+  },
+  directives: {
+    SafeHtml,
   },
   props: {
     loading: {
@@ -23,9 +32,47 @@ export default {
       default: () => {},
     },
   },
+  methods: {
+    showPopover({ startEventHtmlDescription, endEventHtmlDescription }) {
+      return startEventHtmlDescription || endEventHtmlDescription;
+    },
+  },
+  popoverOptions: {
+    triggers: 'hover',
+    placement: 'bottom',
+  },
 };
 </script>
 <template>
   <gl-skeleton-loading v-if="loading" :lines="2" class="h-auto pt-2 pb-1" />
-  <gl-path v-else :key="selectedStage.id" :items="stages" @selected="$emit('selected', $event)" />
+  <gl-path v-else :key="selectedStage.id" :items="stages" @selected="$emit('selected', $event)">
+    <template #default="{ pathItem, pathId }">
+      <gl-popover
+        v-if="showPopover(pathItem)"
+        v-bind="$options.popoverOptions"
+        :target="pathId"
+        data-testid="stage-item-popover"
+      >
+        <template #title>{{ pathItem.title }}</template>
+        <div class="gl-display-table">
+          <div v-if="pathItem.startEventHtmlDescription" class="gl-display-table-row">
+            <div class="gl-display-table-cell gl-pr-4 gl-pb-4">
+              {{ s__('ValueStreamEvent|Start') }}
+            </div>
+            <div
+              v-safe-html="pathItem.startEventHtmlDescription"
+              class="gl-display-table-cell gl-pb-4 stage-event-description"
+            ></div>
+          </div>
+          <div v-if="pathItem.endEventHtmlDescription" class="gl-display-table-row">
+            <div class="gl-display-table-cell gl-pr-4">{{ s__('ValueStreamEvent|Stop') }}</div>
+            <div
+              v-safe-html="pathItem.endEventHtmlDescription"
+              class="gl-display-table-cell stage-event-description"
+            ></div>
+          </div>
+        </div>
+      </gl-popover>
+    </template>
+  </gl-path>
 </template>

ee/app/assets/stylesheets/page_bundles/cycle_analytics.scss

@@ -38,3 +38,8 @@
     0 0.25rem 0.75rem $gl-btn-active-background;
 }
 
+// Since backend wraps event description in a paragraph
+// we need to remove common styles, i.e., spacing
+.stage-event-description p {
+  margin: 0 !important;
+}

ee/spec/frontend/analytics/cycle_analytics/components/__snapshots__/path_navigation_spec.js.snap

+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`PathNavigation displays correctly loading is false matches the snapshot 1`] = `
+<div
+  class="gl-path-nav"
+  data-testid="gl-path-nav"
+  style="--path-bg-color: white;"
+>
+  <span
+    class="gl-path-fade gl-path-fade-left"
+    style="display: none;"
+  >
+    <button
+      aria-label="Scroll left"
+      class="gl-clear-icon-button"
+    >
+      <svg
+        aria-hidden="true"
+        class="gl-icon s32"
+        data-testid="chevron-left-icon"
+      >
+        <use
+          href="#chevron-left"
+        />
+      </svg>
+    </button>
+  </span>
+   
+  <ul
+    class="gl-path-nav-list"
+  >
+    <li
+      class="gl-path-nav-list-item"
+      id="path-6-item-0"
+    >
+      <button
+        class="gl-path-button gl-path-active-item-indigo"
+      >
+        <!---->
+        
+        Issue
+        <!---->
+      </button>
+       
+      <div
+        class="gl-popover"
+        data-testid="stage-item-popover"
+      >
+         
+        <div
+          class="gl-display-table"
+        >
+          <div
+            class="gl-display-table-row"
+          >
+            <div
+              class="gl-display-table-cell gl-pr-4 gl-pb-4"
+            >
+              
+            Start
+          
+            </div>
+             
+            <div
+              class="gl-display-table-cell gl-pb-4 stage-event-description"
+            >
+              <p
+                data-sourcepos="1:1-1:13"
+                dir="auto"
+              >
+                Issue created
+              </p>
+            </div>
+          </div>
+           
+          <div
+            class="gl-display-table-row"
+          >
+            <div
+              class="gl-display-table-cell gl-pr-4"
+            >
+              Stop
+            </div>
+             
+            <div
+              class="gl-display-table-cell stage-event-description"
+            >
+              <p
+                data-sourcepos="1:1-1:71"
+                dir="auto"
+              >
+                Issue first associated with a milestone or issue first added to a board
+              </p>
+            </div>
+          </div>
+        </div>
+        Issue
+      </div>
+    </li>
+    <li
+      class="gl-path-nav-list-item"
+      id="path-6-item-1"
+    >
+      <button
+        class="gl-path-button"
+      >
+        <!---->
+        
+        Plan
+        <!---->
+      </button>
+       
+      <div
+        class="gl-popover"
+        data-testid="stage-item-popover"
+      >
+         
+        <div
+          class="gl-display-table"
+        >
+          <div
+            class="gl-display-table-row"
+          >
+            <div
+              class="gl-display-table-cell gl-pr-4 gl-pb-4"
+            >
+              
+            Start
+          
+            </div>
+             
+            <div
+              class="gl-display-table-cell gl-pb-4 stage-event-description"
+            >
+              <p
+                data-sourcepos="1:1-1:71"
+                dir="auto"
+              >
+                Issue first associated with a milestone or issue first added to a board
+              </p>
+            </div>
+          </div>
+           
+          <div
+            class="gl-display-table-row"
+          >
+            <div
+              class="gl-display-table-cell gl-pr-4"
+            >
+              Stop
+            </div>
+             
+            <div
+              class="gl-display-table-cell stage-event-description"
+            >
+              <p
+                data-sourcepos="1:1-1:33"
+                dir="auto"
+              >
+                Issue first mentioned in a commit
+              </p>
+            </div>
+          </div>
+        </div>
+        Plan
+      </div>
+    </li>
+    <li
+      class="gl-path-nav-list-item"
+      id="path-6-item-2"
+    >
+      <button
+        class="gl-path-button"
+      >
+        <!---->
+        
+        Code
+        <!---->
+      </button>
+       
+      <div
+        class="gl-popover"
+        data-testid="stage-item-popover"
+      >
+         
+        <div
+          class="gl-display-table"
+        >
+          <div
+            class="gl-display-table-row"
+          >
+            <div
+              class="gl-display-table-cell gl-pr-4 gl-pb-4"
+            >
+              
+            Start
+          
+            </div>
+             
+            <div
+              class="gl-display-table-cell gl-pb-4 stage-event-description"
+            >
+              <p
+                data-sourcepos="1:1-1:33"
+                dir="auto"
+              >
+                Issue first mentioned in a commit
+              </p>
+            </div>
+          </div>
+           
+          <div
+            class="gl-display-table-row"
+          >
+            <div
+              class="gl-display-table-cell gl-pr-4"
+            >
+              Stop
+            </div>
+             
+            <div
+              class="gl-display-table-cell stage-event-description"
+            >
+              <p
+                data-sourcepos="1:1-1:21"
+                dir="auto"
+              >
+                Merge request created
+              </p>
+            </div>
+          </div>
+        </div>
+        Code
+      </div>
+    </li>
+  </ul>
+   
+  <span
+    class="gl-path-fade gl-path-fade-right"
+    style="display: none;"
+  >
+    <button
+      aria-label="Scroll right"
+      class="gl-clear-icon-button"
+    >
+      <svg
+        aria-hidden="true"
+        class="gl-icon s32"
+        data-testid="chevron-right-icon"
+      >
+        <use
+          href="#chevron-right"
+        />
+      </svg>
+    </button>
+  </span>
+</div>
+`;

ee/spec/frontend/analytics/cycle_analytics/components/path_navigation_spec.js

@@ -56,6 +56,42 @@ describe('PathNavigation', () => {
         it('hides the gl-skeleton-loading component', () => {
           expect(wrapper.find(GlSkeletonLoading).exists()).toBe(false);
         });
+
+        it('matches the snapshot', () => {
+          expect(wrapper.element).toMatchSnapshot();
+        });
+
+        describe('popovers', () => {
+          const modifiedStages = [
+            ...transformedStagePathData.slice(0, 2),
+            {
+              ...transformedStagePathData[2],
+              startEventHtmlDescription: null,
+              endEventHtmlDescription: null,
+            },
+          ];
+
+          beforeEach(() => {
+            wrapper = createComponent({ stages: modifiedStages });
+          });
+
+          it('renders popovers only for stages with either a start event and/or and end event', () => {
+            expect(wrapper.findAll('[data-testid="stage-item-popover"]')).toHaveLength(2);
+          });
+
+          it('shows the sanitized start event description for the first stage item', () => {
+            const firsPpopover = wrapper.findAll('[data-testid="stage-item-popover"]').at(0);
+            const expectedStartEventDescription = 'Issue created';
+            expect(firsPpopover.text()).toContain(expectedStartEventDescription);
+          });
+
+          it('shows the sanitized end event description for the first stage item', () => {
+            const firsPpopover = wrapper.findAll('[data-testid="stage-item-popover"]').at(0);
+            const expectedStartEventDescription =
+              'Issue first associated with a milestone or issue first added to a board';
+            expect(firsPpopover.text()).toContain(expectedStartEventDescription);
+          });
+        });
       });
 
       describe('is true', () => {

locale/gitlab.pot

@@ -33456,6 +33456,12 @@ msgstr ""
 msgid "ValueStreamAnalytics|Median time from issue created to issue closed."
 msgstr ""
+msgid "ValueStreamEvent|Start"
+msgstr ""
+
+msgid "ValueStreamEvent|Stop"
+msgstr ""
+
 msgid "ValueStream|The Default Value Stream cannot be deleted"
 msgstr ""