Add 14 day grace period for expired subscriptions

Show the "you've been downgraded" expiration message 14 days
after a .com subscription ends.

part of:
https://gitlab.com/gitlab-org/growth/product/-/issues/1606

ee/app/presenters/subscription_presenter.rb

 # frozen_string_literal: true
 
 class SubscriptionPresenter < Gitlab::View::Presenter::Delegated
+  GRACE_PERIOD_EXTENSION_DAYS = 14.days
+
   presents :subscription
 
   def block_changes?
-    expired?
+    will_block_changes? && (block_changes_at < Date.today)
   end
 
   def plan
@@ -22,7 +24,12 @@ class SubscriptionPresenter < Gitlab::View::Presenter::Delegated
   def expires_at
     end_date
   end
-  alias_method :block_changes_at, :expires_at
+
+  def block_changes_at
+    return unless end_date
+
+    end_date + GRACE_PERIOD_EXTENSION_DAYS
+  end
 
   def remaining_days
     return unless end_date
@@ -33,6 +40,6 @@ class SubscriptionPresenter < Gitlab::View::Presenter::Delegated
   end
 
   def will_block_changes?
-    true
+    end_date.present?
   end
 end

ee/changelogs/unreleased/jswain_subscription_banner_add_14_day_normal_grace_period.yml

+---
+title: Subscription Banner has 14 day grace period
+merge_request: 37378
+author:
+type: changed

ee/spec/presenters/subscription_presenter_spec.rb

@@ -47,27 +47,79 @@ RSpec.describe SubscriptionPresenter do
   describe '#block_changes_at' do
     subject { presenter.block_changes_at }
 
-    it { is_expected.to eq(subscription.end_date) }
+    it { is_expected.to eq(subscription.end_date + 14.days) }
+
+    context 'when end_date is nil' do
+      it 'is nil' do
+        allow(subscription).to receive(:end_date).and_return(nil)
+
+        expect(subject).to be nil
+      end
+    end
   end
 
   describe '#block_changes?' do
     subject { presenter.block_changes? }
 
-    it { is_expected.to be false }
+    let(:today) { Time.utc(2020, 3, 7, 10) }
+
+    before do
+      allow(subscription).to receive(:end_date).and_return(end_date)
+    end
+
+    context 'end_date is nil' do
+      let(:end_date) { nil }
+
+      it { is_expected.to be false }
+    end
+
+    context 'is not expired' do
+      let(:end_date) { today + 1.day }
+
+      it 'is false' do
+        Timecop.freeze(today) do
+          expect(subject).to be false
+        end
+      end
+    end
 
     context 'is expired' do
-      before do
-        allow(subscription).to receive(:expired?).and_return(true)
+      context 'is not past grace period' do
+        let(:end_date) { today - 13.days }
+
+        it 'is false' do
+          Timecop.freeze(today) do
+            expect(subject).to be false
+          end
+        end
       end
 
-      it { is_expected.to be true }
+      context 'is past grace period' do
+        let(:end_date) { today - 15.days }
+
+        it 'is true' do
+          Timecop.freeze(today) do
+            expect(subject).to be true
+          end
+        end
+      end
     end
   end
 
   describe '#will_block_changes?' do
     subject { presenter.will_block_changes? }
 
-    it { is_expected.to be true }
+    context 'when end_date exists' do
+      it { is_expected.to be true }
+    end
+
+    context 'when end_date does not exist' do
+      it 'is false' do
+        allow(subscription).to receive(:end_date).and_return(nil)
+
+        expect(subject).to be false
+      end
+    end
   end
 
   describe '#remaining_days' do