Decrement participant count when overriding version

Author: santib

lib/split/persistence/dual_adapter.rb

@@ -41,13 +41,26 @@ def [](key)
 
       def []=(key, value)
         @logged_in_adapter[key] = value if @logged_in
+        old_value = @logged_out_adapter[key]
         @logged_out_adapter[key] = value
+
+        decrement_participation(key, old_value) if decrement_participation?(old_value, value)
       end
 
       def delete(key)
         @logged_in_adapter.delete(key)
         @logged_out_adapter.delete(key)
       end
+
+      private
+
+      def decrement_participation?(old_value, value)
+        !old_value.nil? && !value.nil? && old_value != value
+      end
+
+      def decrement_participation(key, value)
+        Split.redis.hincrby("#{key}:#{value}", 'participant_count', -1)
+      end
     end
   end
 end

spec/persistence/dual_adapter_spec.rb

@@ -26,6 +26,7 @@
     it '#[]=' do
       expect(logged_in_adapter_instance).to receive(:[]=).with('my_key', 'my_value')
       expect(logged_out_adapter_instance).to receive(:[]=).with('my_key', 'my_value')
+      expect(logged_out_adapter_instance).to receive(:[]).with('my_key') { nil }
       subject['my_key'] = 'my_value'
     end
 
@@ -60,6 +61,7 @@
     it '#[]=' do
       expect_any_instance_of(logged_in_adapter).not_to receive(:[]=)
       expect(logged_out_adapter_instance).to receive(:[]=).with('my_key', 'my_value')
+      expect(logged_out_adapter_instance).to receive(:[]).with('my_key') { nil }
       subject['my_key'] = 'my_value'
     end