Use feature flag for new CI minutes monthly tracking

https://gitlab.com/gitlab-org/gitlab/-/issues/277448

ee/app/models/ci/minutes/quota.rb

@@ -41,17 +41,21 @@ module Ci
 
       def total_minutes_used
         strong_memoize(:total_minutes_used) do
-          # TODO: use namespace.new_monthly_ci_minutes_enabled? to switch to
-          # ::Ci::Minutes::NamespaceMonthlyUsage.find_or_create_current(namespace.id).amount_used.to_i
-          namespace.namespace_statistics&.shared_runners_seconds.to_i / 60
+          if namespace.new_monthly_ci_minutes_enabled?
+            current_usage.amount_used.to_i
+          else
+            namespace.namespace_statistics&.shared_runners_seconds.to_i / 60
+          end
         end
       end
 
       def reset_date
         strong_memoize(:reset_date) do
-          # TODO: use namespace.new_monthly_ci_minutes_enabled? to switch to
-          # ::Ci::Minutes::NamespaceMonthlyUsage.find_or_create_current(namespace.id).date
-          namespace.namespace_statistics&.shared_runners_seconds_last_reset
+          if namespace.new_monthly_ci_minutes_enabled?
+            current_usage.date
+          else
+            namespace.namespace_statistics&.shared_runners_seconds_last_reset
+          end
         end
       end
 
@@ -102,6 +106,10 @@ module Ci
 
       private
 
+      def current_usage
+        @current_usage ||= ::Ci::Minutes::NamespaceMonthlyUsage.find_or_create_current(namespace_id: namespace.id)
+      end
+
       def monthly_minutes_available?
         total_minutes_used <= monthly_minutes
       end

ee/spec/features/admin/admin_reset_pipeline_minutes_spec.rb

@@ -29,7 +29,8 @@ RSpec.describe 'Reset namespace pipeline minutes', :js do
         expect(current_path).to include(namespace.path)
 
         expect(namespace.reload.ci_minutes_quota.total_minutes_used).to eq(0)
-        expect(namespace.ci_minutes_quota.reset_date).to be_like_time(time)
+        expect(namespace.ci_minutes_quota.reset_date.month).to eq(time.month)
+        expect(namespace.ci_minutes_quota.reset_date.year).to eq(time.year)
       end
     end
   end

ee/spec/models/ci/minutes/quota_spec.rb

@@ -238,16 +238,26 @@ RSpec.describe Ci::Minutes::Quota do
   describe '#reset_date' do
     subject(:reset_date) { quota.reset_date }
 
-    let(:reset_time) { Date.new(2021, 10, 14) }
+    let(:current_time) { Date.new(2021, 10, 14) }
 
     let(:namespace) do
-      travel_to(reset_time) do
+      travel_to(current_time) do
         create(:namespace, :with_ci_minutes)
       end
     end
 
-    it 'corresponds to the reset time' do
-      expect(reset_date).to eq(reset_time)
+    it 'corresponds to the beginning of the current month' do
+      expect(reset_date).to eq(Date.new(2021, 10, 1))
+    end
+
+    context 'when feature flag ci_use_new_monthly_minutes is disabled' do
+      before do
+        stub_feature_flags(ci_use_new_monthly_minutes: false)
+      end
+
+      it 'corresponds to the current time' do
+        expect(reset_date).to eq(current_time)
+      end
     end
   end
 end