Make days until deprecation method private

We decided to make the .days_until_deprecation method private
as its functionality is tested in other tests. This commit also
removes the associated test for the newly private method.

changelogs/unreleased/limit-db-deprecation-notice-window.yml

+---
+title: Limit database deprecation notice window
+merge_request: 37009
+author:
+type: changed

lib/gitlab/config_checker/external_database_checker.rb

@@ -23,7 +23,7 @@ module Gitlab
             }
         end
 
-        if Gitlab::Database.postgresql_upcoming_deprecation?
+        if Gitlab::Database.postgresql_upcoming_deprecation? && Gitlab::Database.within_deprecation_notice_window?
           upcoming_deprecation = Gitlab::Database::UPCOMING_POSTGRES_VERSION_DETAILS
 
           notices <<

lib/gitlab/database.rb

@@ -13,11 +13,15 @@ module Gitlab
     # so administrators can prepare to upgrade
     UPCOMING_POSTGRES_VERSION_DETAILS = {
       gl_version: '13.6.0',
-      gl_version_date: 'November 2020',
+      gl_version_date: 'November 22, 2020',
       pg_version_minimum: 12,
       url: 'https://gitlab.com/groups/gitlab-org/-/epics/2374'
     }.freeze
 
+    # Specifies the maximum number of days in advance to display a notice
+    # regarding an upcoming PostgreSQL version deprecation.
+    DEPRECATION_WINDOW_DAYS = 90
+
     # https://www.postgresql.org/docs/9.2/static/datatype-numeric.html
     MAX_INT_VALUE = 2147483647
 
@@ -119,6 +123,18 @@ module Gitlab
       version.to_f < UPCOMING_POSTGRES_VERSION_DETAILS[:pg_version_minimum]
     end
 
+    def self.days_until_deprecation
+      (
+        Date.parse(UPCOMING_POSTGRES_VERSION_DETAILS[:gl_version_date]) -
+        Date.today
+      ).to_i
+    end
+    private_class_method :days_until_deprecation
+
+    def self.within_deprecation_notice_window?
+      days_until_deprecation <= DEPRECATION_WINDOW_DAYS
+    end
+
     def self.check_postgres_version_and_print_warning
       return if Gitlab::Database.postgresql_minimum_supported_version?
       return if Gitlab::Runtime.rails_runner?

spec/lib/gitlab/config_checker/external_database_checker_spec.rb

@@ -36,9 +36,23 @@ RSpec.describe Gitlab::ConfigChecker::ExternalDatabaseChecker do
         allow(Gitlab::Database).to receive(:postgresql_upcoming_deprecation?).and_return(true)
       end
 
-      it 'only returns notice about an upcoming deprecation' do
-        is_expected.to include(a_hash_including(message: include(upcoming_deprecation_warning)))
-        is_expected.not_to include(a_hash_including(message: include(deprecation_warning)))
+      context 'inside the deprecation notice window' do
+        before do
+          allow(Gitlab::Database).to receive(:within_deprecation_notice_window?).and_return(true)
+        end
+
+        it 'only returns notice about an upcoming deprecation' do
+          is_expected.to include(a_hash_including(message: include(upcoming_deprecation_warning)))
+          is_expected.not_to include(a_hash_including(message: include(deprecation_warning)))
+        end
+      end
+
+      context 'outside the deprecation notice window' do
+        before do
+          allow(Gitlab::Database).to receive(:within_deprecation_notice_window?).and_return(false)
+        end
+
+        it { is_expected.to be_empty }
       end
     end
 
@@ -48,11 +62,28 @@ RSpec.describe Gitlab::ConfigChecker::ExternalDatabaseChecker do
         allow(Gitlab::Database).to receive(:postgresql_upcoming_deprecation?).and_return(true)
       end
 
-      it 'returns notice about deprecated database version and an upcoming deprecation' do
-        is_expected.to include(
-          a_hash_including(message: include(deprecation_warning)),
-          a_hash_including(message: include(upcoming_deprecation_warning))
-        )
+      context 'inside the deprecation notice window' do
+        before do
+          allow(Gitlab::Database).to receive(:within_deprecation_notice_window?).and_return(true)
+        end
+
+        it 'returns notice about deprecated database version and an upcoming deprecation' do
+          is_expected.to include(
+            a_hash_including(message: include(deprecation_warning)),
+            a_hash_including(message: include(upcoming_deprecation_warning))
+          )
+        end
+      end
+
+      context 'outside the deprecation notice window' do
+        before do
+          allow(Gitlab::Database).to receive(:within_deprecation_notice_window?).and_return(false)
+        end
+
+        it 'only returns notice about deprecated database version' do
+          is_expected.to include(a_hash_including(message: include(deprecation_warning)))
+          is_expected.not_to include(a_hash_including(message: include(upcoming_deprecation_warning)))
+        end
       end
     end
   end

spec/lib/gitlab/database_spec.rb

@@ -129,6 +129,26 @@ RSpec.describe Gitlab::Database do
     end
   end
 
+  describe '.within_deprecation_notice_window?' do
+    using RSpec::Parameterized::TableSyntax
+
+    where(:case_name, :days, :result) do
+      'outside window'  | Gitlab::Database::DEPRECATION_WINDOW_DAYS + 1 | false
+      'equal to window' | Gitlab::Database::DEPRECATION_WINDOW_DAYS     | true
+      'within window'   | Gitlab::Database::DEPRECATION_WINDOW_DAYS - 1 | true
+    end
+
+    with_them do
+      it "returns #{params[:result]} when #{params[:case_name]}" do
+        allow(Date)
+          .to receive(:today)
+          .and_return Date.parse(Gitlab::Database::UPCOMING_POSTGRES_VERSION_DETAILS[:gl_version_date]) - days
+
+        expect(described_class.within_deprecation_notice_window?).to eq(result)
+      end
+    end
+  end
+
   describe '.check_postgres_version_and_print_warning' do
     subject { described_class.check_postgres_version_and_print_warning }