refactored a bunch of stuff based on feedback

app/models/cycle_analytics.rb

@@ -17,7 +17,7 @@ class CycleAnalytics
   end
 
   def no_stats?
-    stats.map { |hash| hash[:value] }.compact.empty?
+    stats.all? { hash[:value].nil? }
   end
 
   def permissions(user:)
@@ -32,7 +32,7 @@ class CycleAnalytics
 
   def stats_per_stage
     STAGES.map do |stage_name|
-      self[stage_name].median_data
+      self[stage_name].as_json
     end
   end
 end

lib/gitlab/cycle_analytics/base_event_fetcher.rb

@@ -42,7 +42,7 @@ module Gitlab
       end
 
       def default_order
-        @options[:start_time_attrs].is_a?(Array) ? @options[:start_time_attrs].first : @options[:start_time_attrs]
+        [@options[:start_time_attrs]].flatten.first
       end
 
       def serialize(_event)

lib/gitlab/cycle_analytics/base_stage.rb

@@ -8,17 +8,11 @@ module Gitlab
         @options = options
       end
 
-      def event
-        @event ||= Gitlab::CycleAnalytics::Event[name].new(project: @project,
-                                                           stage: name,
-                                                           options: event_options)
-      end
-
       def events
-        event.fetch
+        event_fetcher.fetch
       end
 
-      def median_data
+      def as_json
         AnalyticsStageSerializer.new.represent(self).as_json
       end
 
@@ -35,7 +29,7 @@ module Gitlab
         # cycle analytics stage.
         interval_query = Arel::Nodes::As.new(
           cte_table,
-          subtract_datetimes(base_query.dup, @start_time_attrs, @end_time_attrs, name.to_s))
+          subtract_datetimes(base_query.dup, start_time_attrs, end_time_attrs, name.to_s))
 
         median_datetime(cte_table, interval_query, name)
       end
@@ -46,8 +40,14 @@ module Gitlab
 
       private
 
+      def event_fetcher
+        @event_fetcher ||= Gitlab::CycleAnalytics::EventFetcher[name].new(project: @project,
+                                                                   stage: name,
+                                                                   options: event_options)
+      end
+
       def event_options
-        @options.merge(start_time_attrs: @start_time_attrs, end_time_attrs: @end_time_attrs)
+        @options.merge(start_time_attrs: start_time_attrs, end_time_attrs: end_time_attrs)
       end
     end
   end

lib/gitlab/cycle_analytics/code_stage.rb

 module Gitlab
   module CycleAnalytics
     class CodeStage < BaseStage
-      def initialize(*args)
-        @start_time_attrs = issue_metrics_table[:first_mentioned_in_commit_at]
-        @end_time_attrs = mr_table[:created_at]
+      def start_time_attrs
+        @start_time_attrs ||= issue_metrics_table[:first_mentioned_in_commit_at]
+      end
 
-        super(*args)
+      def end_time_attrs
+        @end_time_attrs ||= mr_table[:created_at]
       end
 
       def name

lib/gitlab/cycle_analytics/event.rb → lib/gitlab/cycle_analytics/event_fetcher.rb

 module Gitlab
   module CycleAnalytics
-    module Event
+    module EventFetcher
       def self.[](stage_name)
         CycleAnalytics.const_get("#{stage_name.to_s.camelize}EventFetcher")
       end

lib/gitlab/cycle_analytics/issue_stage.rb

 module Gitlab
   module CycleAnalytics
     class IssueStage < BaseStage
-      def initialize(*args)
-        @start_time_attrs = issue_table[:created_at]
-        @end_time_attrs = [issue_metrics_table[:first_associated_with_milestone_at],
-                           issue_metrics_table[:first_added_to_board_at]]
+      def start_time_attrs
+        @start_time_attrs ||= issue_table[:created_at]
+      end
 
-        super(*args)
+      def end_time_attrs
+        @end_time_attrs ||= [issue_metrics_table[:first_associated_with_milestone_at],
+                             issue_metrics_table[:first_added_to_board_at]]
       end
 
       def name

lib/gitlab/cycle_analytics/plan_stage.rb

 module Gitlab
   module CycleAnalytics
     class PlanStage < BaseStage
-      def initialize(*args)
-        @start_time_attrs = [issue_metrics_table[:first_associated_with_milestone_at],
+      def start_time_attrs
+        @start_time_attrs ||= [issue_metrics_table[:first_associated_with_milestone_at],
                                issue_metrics_table[:first_added_to_board_at]]
-        @end_time_attrs = issue_metrics_table[:first_mentioned_in_commit_at]
+      end
 
-        super(*args)
+      def end_time_attrs
+        @end_time_attrs ||= issue_metrics_table[:first_mentioned_in_commit_at]
       end
 
       def name

lib/gitlab/cycle_analytics/production_stage.rb

@@ -3,11 +3,12 @@ module Gitlab
     class ProductionStage < BaseStage
       include ProductionHelper
 
-      def initialize(*args)
-        @start_time_attrs = issue_table[:created_at]
-        @end_time_attrs = mr_metrics_table[:first_deployed_to_production_at]
+      def start_time_attrs
+        @start_time_attrs ||= issue_table[:created_at]
+      end
 
-        super(*args)
+      def end_time_attrs
+        @end_time_attrs ||= mr_metrics_table[:first_deployed_to_production_at]
       end
 
       def name

lib/gitlab/cycle_analytics/review_stage.rb

 module Gitlab
   module CycleAnalytics
     class ReviewStage < BaseStage
-      def initialize(*args)
-        @start_time_attrs = mr_table[:created_at]
-        @end_time_attrs = mr_metrics_table[:merged_at]
+      def start_time_attrs
+        @start_time_attrs ||= mr_table[:created_at]
+      end
 
-        super(*args)
+      def end_time_attrs
+        @end_time_attrs ||= mr_metrics_table[:merged_at]
       end
 
       def name

lib/gitlab/cycle_analytics/staging_stage.rb

@@ -2,12 +2,12 @@ module Gitlab
   module CycleAnalytics
     class StagingStage < BaseStage
       include ProductionHelper
+      def start_time_attrs
+        @start_time_attrs ||= mr_metrics_table[:merged_at]
+      end
 
-      def initialize(*args)
-        @start_time_attrs = mr_metrics_table[:merged_at]
-        @end_time_attrs = mr_metrics_table[:first_deployed_to_production_at]
-
-        super(*args)
+      def end_time_attrs
+        @end_time_attrs ||= mr_metrics_table[:first_deployed_to_production_at]
       end
 
       def name

lib/gitlab/cycle_analytics/test_stage.rb

 module Gitlab
   module CycleAnalytics
     class TestStage < BaseStage
-      def initialize(*args)
-        @start_time_attrs =  mr_metrics_table[:latest_build_started_at]
-        @end_time_attrs = mr_metrics_table[:latest_build_finished_at]
+      def start_time_attrs
+        @start_time_attrs ||= mr_metrics_table[:latest_build_started_at]
+      end
 
-        super(*args)
+      def end_time_attrs
+        @end_time_attrs ||= mr_metrics_table[:latest_build_finished_at]
       end
 
       def name

spec/lib/gitlab/cycle_analytics/shared_stage_spec.rb

@@ -9,15 +9,15 @@ shared_examples 'base stage' do
   end
 
   it 'has the median data value' do
-    expect(stage.median_data[:value]).not_to be_nil
+    expect(stage.as_json[:value]).not_to be_nil
   end
 
   it 'has the median data stage' do
-    expect(stage.median_data[:title]).not_to be_nil
+    expect(stage.as_json[:title]).not_to be_nil
   end
 
   it 'has the median data description' do
-    expect(stage.median_data[:description]).not_to be_nil
+    expect(stage.as_json[:description]).not_to be_nil
   end
 
   it 'has the title' do