Conditional enforcement of namespace storage limit

- Adds enforce_limit? method to RootStorageSize to determine if
  storage limits should be enforced.
- Using enforce_limit? as a guard clause for above_size_limit? method.

ee/app/models/ee/namespace/root_storage_size.rb

@@ -5,12 +5,15 @@ module EE
     CURRENT_SIZE_CACHE_KEY = 'root_storage_current_size'
     LIMIT_CACHE_KEY = 'root_storage_size_limit'
     EXPIRATION_TIME = 10.minutes
+    EFFECTIVE_DATE = 99.years.from_now.to_date
+    ENFORCEMENT_DATE = 100.years.from_now.to_date
 
     def initialize(root_namespace)
       @root_namespace = root_namespace
     end
 
     def above_size_limit?
+      return false unless enforce_limit?
       return false if root_namespace.temporary_storage_increase_enabled?
 
       usage_ratio > 1
@@ -35,8 +38,18 @@ module EE
       end
     end
 
+    def enforce_limit?
+      return false if Date.current < ENFORCEMENT_DATE
+
+      return true unless closest_gitlab_subscription&.has_a_paid_hosted_plan?
+
+      closest_gitlab_subscription.start_date >= EFFECTIVE_DATE
+    end
+
     private
 
     attr_reader :root_namespace
+
+    delegate :closest_gitlab_subscription, to: :root_namespace
   end
 end

ee/spec/models/namespace/root_storage_size_spec.rb

@@ -25,29 +25,43 @@ RSpec.describe Namespace::RootStorageSize, type: :model do
       allow(namespace).to receive(:temporary_storage_increase_enabled?).and_return(false)
     end
 
-    context 'when limit is 0' do
-      let(:limit) { 0 }
+    context 'when limit enforcement is off' do
+      before do
+        allow(model).to receive(:enforce_limit?).and_return(false)
+      end
 
       it { is_expected.to eq(false) }
     end
 
-    context 'when below limit' do
-      it { is_expected.to eq(false) }
-    end
+    context 'when limit enforcement is on' do
+      before do
+        allow(model).to receive(:enforce_limit?).and_return(true)
+      end
 
-    context 'when above limit' do
-      let(:current_size) { 101.megabytes }
+      context 'when limit is 0' do
+        let(:limit) { 0 }
 
-      context 'when temporary storage increase is disabled' do
-        it { is_expected.to eq(true) }
+        it { is_expected.to eq(false) }
       end
 
-      context 'when temporary storage increase is enabled' do
-        before do
-          allow(namespace).to receive(:temporary_storage_increase_enabled?).and_return(true)
+      context 'when below limit' do
+        it { is_expected.to eq(false) }
+      end
+
+      context 'when above limit' do
+        let(:current_size) { 101.megabytes }
+
+        context 'when temporary storage increase is disabled' do
+          it { is_expected.to eq(true) }
         end
 
-        it { is_expected.to eq(false) }
+        context 'when temporary storage increase is enabled' do
+          before do
+            allow(namespace).to receive(:temporary_storage_increase_enabled?).and_return(true)
+          end
+
+          it { is_expected.to eq(false) }
+        end
       end
     end
   end
@@ -133,4 +147,56 @@ RSpec.describe Namespace::RootStorageSize, type: :model do
       end
     end
   end
+
+  describe '#enforce_limit?' do
+    subject { model.enforce_limit? }
+
+    around do |example|
+      Timecop.travel(current_date) { example.run }
+    end
+
+    context 'when current date is before enforcement date' do
+      let(:current_date) { described_class::ENFORCEMENT_DATE - 1.day }
+
+      it { is_expected.to eq(false) }
+    end
+
+    context 'when current date is on or after enforcement date' do
+      let(:current_date) { described_class::ENFORCEMENT_DATE }
+
+      context 'when no subscription is found for namespace' do
+        before do
+          subscription.destroy!
+        end
+
+        it { is_expected.to eq(true) }
+      end
+
+      context 'when subscription is for a free plan' do
+        let!(:subscription) do
+          create(:gitlab_subscription, namespace: namespace, hosted_plan: create(:free_plan))
+        end
+
+        it { is_expected.to eq(true) }
+      end
+
+      context 'when subscription is for a paid plan' do
+        before do
+          allow(subscription).to receive(:start_date).and_return(start_date)
+        end
+
+        context 'when subscription start date is before effective date' do
+          let(:start_date) { described_class::EFFECTIVE_DATE - 1.day }
+
+          it { is_expected.to eq(false) }
+        end
+
+        context 'when subscription start date is on or after effective date' do
+          let(:start_date) { described_class::EFFECTIVE_DATE }
+
+          it { is_expected.to eq(true) }
+        end
+      end
+    end
+  end
 end