Expose VSA stage event descriptions

This change exposes stage start and end event description via the value
streams private API.

ee/app/controllers/groups/analytics/cycle_analytics/value_streams_controller.rb

@@ -67,7 +67,7 @@ class Groups::Analytics::CycleAnalytics::ValueStreamsController < Groups::Analyt
   end
 
   def value_streams
-    @group.value_streams.presence || [in_memory_default_value_stream]
+    @group.value_streams.preload_associated_models.presence || [in_memory_default_value_stream]
   end
 
   def in_memory_default_value_stream

ee/app/models/analytics/cycle_analytics/group_value_stream.rb

@@ -10,6 +10,8 @@ class Analytics::CycleAnalytics::GroupValueStream < ApplicationRecord
 
   accepts_nested_attributes_for :stages, allow_destroy: true
 
+  scope :preload_associated_models, -> { includes(:group, stages: [:group, :end_event_label, :start_event_label]) }
+
   def custom?
     name != Analytics::CycleAnalytics::Stages::BaseService::DEFAULT_VALUE_STREAM_NAME
   end

ee/app/serializers/analytics/cycle_analytics/stage_entity.rb

@@ -13,10 +13,26 @@ module Analytics
       expose :end_event_identifier, if: -> (s) { s.custom? }
       expose :start_event_label, using: LabelEntity, if: -> (s) { s.start_event_label_based? }
       expose :end_event_label, using: LabelEntity, if: -> (s) { s.end_event_label_based? }
+      expose :start_event_html_description
+      expose :end_event_html_description
 
       def id
         object.id || object.name
       end
+
+      def start_event_html_description
+        html_description(object.start_event)
+      end
+
+      def end_event_html_description
+        html_description(object.end_event)
+      end
+
+      private
+
+      def html_description(event)
+        Banzai::Renderer.render(event.markdown_description, { group: object.group, project: nil })
+      end
     end
   end
 end

ee/lib/gitlab/analytics/cycle_analytics/stage_events/issue_label_added.rb

@@ -13,6 +13,10 @@ module Gitlab
             :issue_label_added
           end
 
+          def markdown_description
+            s_("CycleAnalyticsEvent|%{label_reference} label was added to the issue") % { label_reference: label.to_reference }
+          end
+
           def object_type
             Issue
           end

ee/lib/gitlab/analytics/cycle_analytics/stage_events/issue_label_removed.rb

@@ -13,6 +13,10 @@ module Gitlab
             :issue_label_removed
           end
 
+          def markdown_description
+            s_("CycleAnalyticsEvent|%{label_reference} label was removed from the issue") % { label_reference: label.to_reference }
+          end
+
           def object_type
             Issue
           end

ee/lib/gitlab/analytics/cycle_analytics/stage_events/merge_request_label_added.rb

@@ -13,6 +13,10 @@ module Gitlab
             :merge_request_label_added
           end
 
+          def markdown_description
+            s_("CycleAnalyticsEvent|%{label_reference} label was added to the merge request") % { label_reference: label.to_reference }
+          end
+
           def object_type
             MergeRequest
           end

ee/lib/gitlab/analytics/cycle_analytics/stage_events/merge_request_label_removed.rb

@@ -13,6 +13,10 @@ module Gitlab
             :merge_request_label_removed
           end
 
+          def markdown_description
+            s_("CycleAnalyticsEvent|%{label_reference} label was removed from the merge request") % { label_reference: label.to_reference }
+          end
+
           def object_type
             MergeRequest
           end

ee/spec/frontend/analytics/cycle_analytics/__snapshots__/utils_spec.js.snap

@@ -5,11 +5,13 @@ Array [
   Object {
     "custom": false,
     "description": "Time before an issue gets scheduled",
+    "endEventHtmlDescription": "<p data-sourcepos=\\"1:1-1:71\\" dir=\\"auto\\">Issue first associated with a milestone or issue first added to a board</p>",
     "hidden": false,
     "id": 1,
     "legend": "",
     "name": "Issue",
     "slug": 1,
+    "startEventHtmlDescription": "<p data-sourcepos=\\"1:1-1:13\\" dir=\\"auto\\">Issue created</p>",
     "title": "Issue",
   },
   Object {

ee/spec/serializers/analytics/cycle_analytics/stage_entity_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Analytics::CycleAnalytics::StageEntity do
+  let(:stage) { build(:cycle_analytics_group_stage, start_event_identifier: :merge_request_created, end_event_identifier: :merge_request_merged) }
+
+  subject(:entity_json) { described_class.new(Analytics::CycleAnalytics::StagePresenter.new(stage)).as_json }
+
+  it 'exposes start and end event descriptions' do
+    expect(entity_json).to have_key(:start_event_html_description)
+    expect(entity_json).to have_key(:end_event_html_description)
+  end
+
+  context 'when label based event is given' do
+    let(:label) { create(:group_label, title: 'test label') }
+    let(:stage) { build(:cycle_analytics_group_stage, group: label.group, start_event_label: label, start_event_identifier: :merge_request_label_added, end_event_identifier: :merge_request_merged) }
+
+    it 'includes the label reference in the description' do
+      expect(entity_json[:start_event_html_description]).to include(label.title)
+    end
+  end
+end

lib/gitlab/analytics/cycle_analytics/stage_events/stage_event.rb

@@ -19,6 +19,10 @@ module Gitlab
             raise NotImplementedError
           end
 
+          def markdown_description
+            self.class.name
+          end
+
           def self.identifier
             raise NotImplementedError
           end

locale/gitlab.pot

@@ -9052,6 +9052,18 @@ msgstr ""
 msgid "Cycle Time"
 msgstr ""
 
+msgid "CycleAnalyticsEvent|%{label_reference} label was added to the issue"
+msgstr ""
+
+msgid "CycleAnalyticsEvent|%{label_reference} label was added to the merge request"
+msgstr ""
+
+msgid "CycleAnalyticsEvent|%{label_reference} label was removed from the issue"
+msgstr ""
+
+msgid "CycleAnalyticsEvent|%{label_reference} label was removed from the merge request"
+msgstr ""
+
 msgid "CycleAnalyticsEvent|Issue closed"
 msgstr ""
 

spec/support/shared_examples/lib/gitlab/cycle_analytics/event_shared_examples.rb

@@ -8,6 +8,7 @@ RSpec.shared_examples_for 'value stream analytics event' do
   it { expect(described_class.identifier).to be_a_kind_of(Symbol) }
   it { expect(instance.object_type.ancestors).to include(ApplicationRecord) }
   it { expect(instance).to respond_to(:timestamp_projection) }
+  it { expect(instance).to respond_to(:markdown_description) }
   it { expect(instance.column_list).to be_a_kind_of(Array) }
 
   describe '#apply_query_customization' do