Merge branch 'define_feature_flags_available_under_class' into 'master'

Move global method to Feature class

See merge request gitlab-org/gitlab!78023

config/initializers/active_record_transaction_observer.rb

@@ -2,17 +2,8 @@
 
 return unless Gitlab.com? || Gitlab.dev_or_test_env?
 
-def feature_flags_available?
-  # When the DBMS is not available, an exception (e.g. PG::ConnectionBad) is raised
-  active_db_connection = ActiveRecord::Base.connection.active? rescue false
-
-  active_db_connection && Feature::FlipperFeature.table_exists?
-rescue ActiveRecord::NoDatabaseError
-  false
-end
-
 Gitlab::Application.configure do
-  if feature_flags_available? && ::Feature.enabled?(:active_record_transactions_tracking, type: :ops, default_enabled: :yaml)
+  if Feature.feature_flags_available? && ::Feature.enabled?(:active_record_transactions_tracking, type: :ops, default_enabled: :yaml)
     Gitlab::Database::Transaction::Observer.register!
   end
 end

lib/feature.rb

@@ -29,6 +29,15 @@ class Feature
   class << self
     delegate :group, to: :flipper
 
+    def feature_flags_available?
+      # When the DBMS is not available, an exception (e.g. PG::ConnectionBad) is raised
+      active_db_connection = ActiveRecord::Base.connection.active? rescue false # rubocop:disable Database/MultipleDatabases
+
+      active_db_connection && Feature::FlipperFeature.table_exists?
+    rescue ActiveRecord::NoDatabaseError
+      false
+    end
+
     def all
       flipper.features.to_a
     end

spec/lib/feature_spec.rb

@@ -11,6 +11,32 @@ RSpec.describe Feature, stub_feature_flags: false do
     skip_feature_flags_yaml_validation
   end
 
+  describe '.feature_flags_available?' do
+    it 'returns false on connection error' do
+      expect(ActiveRecord::Base.connection).to receive(:active?).and_raise(PG::ConnectionBad) # rubocop:disable Database/MultipleDatabases
+
+      expect(described_class.feature_flags_available?).to eq(false)
+    end
+
+    it 'returns false when connection is not active' do
+      expect(ActiveRecord::Base.connection).to receive(:active?).and_return(false) # rubocop:disable Database/MultipleDatabases
+
+      expect(described_class.feature_flags_available?).to eq(false)
+    end
+
+    it 'returns false when the flipper table does not exist' do
+      expect(Feature::FlipperFeature).to receive(:table_exists?).and_return(false)
+
+      expect(described_class.feature_flags_available?).to eq(false)
+    end
+
+    it 'returns false on NoDatabaseError' do
+      expect(Feature::FlipperFeature).to receive(:table_exists?).and_raise(ActiveRecord::NoDatabaseError)
+
+      expect(described_class.feature_flags_available?).to eq(false)
+    end
+  end
+
   describe '.get' do
     let(:feature) { double(:feature) }
     let(:key) { 'my_feature' }