Return 404 when Contribution Analytics feature is not available

See gitlab-ee#2579

app/controllers/ee/groups/application_controller.rb

+module EE
+  module Groups
+    module ApplicationController
+      def check_group_feature_available!(feature)
+        render_404 unless group.feature_available?(feature)
+      end
+
+      def method_missing(method_sym, *arguments, &block)
+        case method_sym.to_s
+        when /\Acheck_group_(.*)_available!\z/
+          check_group_feature_available!($1.to_sym)
+        else
+          super
+        end
+      end
+    end
+  end
+end

app/controllers/groups/analytics_controller.rb

 class Groups::AnalyticsController < Groups::ApplicationController
   before_action :group
+  before_action :check_group_contribution_analytics_available!
 
   layout 'group'
 

app/controllers/groups/application_controller.rb

 class Groups::ApplicationController < ApplicationController
   include RoutableActions
+  prepend EE::Groups::ApplicationController
 
   layout 'group'
 

changelogs/unreleased-ee/tc-namespace-license-checks--contribution-analytics.yml

+---
+title: Add namespace license checks for Contribution Analytics
+merge_request: 2302
+author:

spec/controllers/groups/analytics_controller_spec.rb

@@ -39,6 +39,14 @@ describe Groups::AnalyticsController do
     create_push_event(user3, project)
   end
 
+  it 'returns 404 when feature is not available' do
+    stub_licensed_features(contribution_analytics: false)
+
+    get :show, group_id: group.path
+
+    expect(response).to have_http_status(404)
+  end
+
   it 'sets instance variables properly' do
     get :show, group_id: group.path