Move last reset date of CI minutes behind abstraction method

The method `shared_runners_seconds_last_reset` reads from legacy
tables where CI minutes are tracked. In preparation to switch to
a new monthly tracking (different tables) we need to move this
attribute reader method behind an abstraction so we can eventually
switch the source via a feature flag.

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

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

@@ -47,6 +47,14 @@ module Ci
         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
+        end
+      end
+
       def purchased_minutes
         strong_memoize(:purchased_minutes) do
           namespace.extra_shared_runners_minutes_limit.to_i

ee/app/models/ee/namespace.rb

@@ -79,8 +79,6 @@ module EE
           .or(where.not(last_ci_minutes_usage_notification_level: nil))
       end
 
-      delegate :shared_runners_seconds_last_reset, to: :namespace_statistics, allow_nil: true
-
       delegate :additional_purchased_storage_size, :additional_purchased_storage_size=,
         :additional_purchased_storage_ends_on, :additional_purchased_storage_ends_on=,
         :temporary_storage_increase_ends_on, :temporary_storage_increase_ends_on=,

ee/app/models/ee/project.rb

@@ -190,8 +190,7 @@ module EE
           .order(excess_arel.desc)
       end
 
-      delegate :shared_runners_seconds, :shared_runners_seconds_last_reset,
-        to: :statistics, allow_nil: true
+      delegate :shared_runners_seconds, to: :statistics, allow_nil: true
 
       delegate :ci_minutes_quota, to: :shared_runners_limit_namespace
 

ee/app/views/namespaces/pipelines_quota/_list.haml

@@ -16,7 +16,7 @@
   .row
     .col-sm-6
       %strong
-        - last_reset = namespace.shared_runners_seconds_last_reset
+        - last_reset = minutes_quota.reset_date
         - if last_reset
           = s_('UsageQuota|Usage since')
           = last_reset.strftime('%b %d, %Y')

ee/spec/factories/namespaces.rb

@@ -15,7 +15,11 @@ FactoryBot.modify do
       after(:create) do |namespace, evaluator|
         if evaluator.ci_minutes_used
           create(:ci_namespace_monthly_usage, namespace: namespace, amount_used: evaluator.ci_minutes_used)
-          create(:namespace_statistics, namespace: namespace, shared_runners_seconds: evaluator.ci_minutes_used.minutes)
+
+          create(:namespace_statistics,
+            namespace: namespace,
+            shared_runners_seconds: evaluator.ci_minutes_used.minutes,
+            shared_runners_seconds_last_reset: Time.current)
         end
       end
     end

ee/spec/features/admin/admin_reset_pipeline_minutes_spec.rb

@@ -13,7 +13,7 @@ RSpec.describe 'Reset namespace pipeline minutes', :js do
   end
 
   shared_examples 'resetting pipeline minutes' do
-    context 'when namespace has namespace statistics' do
+    context 'when namespace has minutes used' do
       before do
         set_ci_minutes_used(namespace, 100)
       end
@@ -29,7 +29,7 @@ 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.namespace_statistics.reload.shared_runners_seconds_last_reset).to be_like_time(time)
+        expect(namespace.ci_minutes_quota.reset_date).to be_like_time(time)
       end
     end
   end

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

@@ -189,7 +189,7 @@ RSpec.describe Ci::Minutes::Quota do
     end
   end
 
-  describe 'purchased_minutes_used_up?' do
+  describe '#purchased_minutes_used_up?' do
     subject { quota.purchased_minutes_used_up? }
 
     context 'when quota is enabled' do
@@ -234,4 +234,20 @@ RSpec.describe Ci::Minutes::Quota do
       it { is_expected.to be_falsey }
     end
   end
+
+  describe '#reset_date' do
+    subject(:reset_date) { quota.reset_date }
+
+    let(:reset_time) { Date.new(2021, 10, 14) }
+
+    let(:namespace) do
+      travel_to(reset_time) do
+        create(:namespace, :with_ci_minutes)
+      end
+    end
+
+    it 'corresponds to the reset time' do
+      expect(reset_date).to eq(reset_time)
+    end
+  end
 end

ee/spec/models/ee/namespace_spec.rb

@@ -20,7 +20,6 @@ RSpec.describe Namespace do
   it { is_expected.to have_one :upcoming_reconciliation }
   it { is_expected.to have_many(:ci_minutes_additional_packs) }
 
-  it { is_expected.to delegate_method(:shared_runners_seconds_last_reset).to(:namespace_statistics) }
   it { is_expected.to delegate_method(:trial?).to(:gitlab_subscription) }
   it { is_expected.to delegate_method(:trial_ends_on).to(:gitlab_subscription) }
   it { is_expected.to delegate_method(:trial_starts_on).to(:gitlab_subscription) }

ee/spec/models/project_spec.rb

@@ -11,7 +11,6 @@ RSpec.describe Project do
 
   describe 'associations' do
     it { is_expected.to delegate_method(:shared_runners_seconds).to(:statistics) }
-    it { is_expected.to delegate_method(:shared_runners_seconds_last_reset).to(:statistics) }
 
     it { is_expected.to delegate_method(:ci_minutes_quota).to(:shared_runners_limit_namespace) }
     it { is_expected.to delegate_method(:shared_runners_minutes_limit_enabled?).to(:shared_runners_limit_namespace) }