use request to pass extra parameters

app/serializers/analytics_generic_entity.rb

@@ -17,7 +17,7 @@ class AnalyticsGenericEntity < Grape::Entity
   end
 
   expose :url do |object|
-    url_to("namespace_project_#{object[:entity]}".to_sym, id: object[:iid].to_s)
+    url_to("namespace_project_#{request.entity}".to_sym, id: object[:iid].to_s)
   end
 
   private

lib/gitlab/cycle_analytics/events.rb

@@ -49,10 +49,10 @@ module Gitlab
 
       private
 
-      def parse_event(event)
+      def parse_event(event, entity: :issue)
         event['author'] = User.find(event.remove('author_id'))
 
-        AnalyticsGenericSerializer.new(project: @project).represent(event).as_json
+        AnalyticsGenericSerializer.new(project: @project, entity: entity).represent(event).as_json
       end
 
       def parse_build_event(event)

spec/serializers/analytics_generic_entity_spec.rb

@@ -10,14 +10,14 @@ describe AnalyticsGenericEntity do
       id: "1",
       created_at: "2016-11-12 15:04:02.948604",
       author: user,
-      entity: :merge_request
     }
   }
 
   let(:project) { create(:empty_project) }
+  let(:request) { EntityRequest.new(project: project, entity: :merge_request) }
 
   let(:entity) do
-    described_class.new(entity_hash, request: double, project: project)
+    described_class.new(entity_hash, request: request, project: project)
   end
 
   context 'generic entity' do

spec/serializers/analytics_generic_serializer_spec.rb

@@ -3,7 +3,7 @@ require 'spec_helper'
 describe AnalyticsGenericSerializer do
   let(:serializer) do
     described_class
-      .new(project: project)
+      .new(project: project, entity: :merge_request)
       .represent(resource)
   end
 
@@ -18,7 +18,6 @@ describe AnalyticsGenericSerializer do
       id: "1",
       created_at: "2016-11-12 15:04:02.948604",
       author: user,
-      entity: :merge_request
     }
   }