Expose optional unit in Analytics Summary Entity

app/serializers/analytics_summary_entity.rb

@@ -3,4 +3,5 @@
 class AnalyticsSummaryEntity < Grape::Entity
   expose :value, safe: true
   expose :title
+  expose :unit, if: { with_unit: true }
 end

spec/serializers/analytics_summary_serializer_spec.rb

@@ -28,4 +28,18 @@ describe AnalyticsSummarySerializer do
   it 'contains important elements of AnalyticsStage' do
     expect(subject).to include(:title, :value)
   end
+
+  it 'does not include unit' do
+    expect(subject).not_to include(:unit)
+  end
+
+  context 'when representing with unit' do
+    let(:resource) { { title: 'frequency', value: 1.12, unit: 'per day' } }
+
+    subject { described_class.new.represent(resource, with_unit: true) }
+
+    it 'contains unit' do
+      expect(subject).to include(:unit)
+    end
+  end
 end