Store attributes as they are instead of converting them into Strings

test/unit/active_model/serializer/attributes_test.rb

@@ -9,19 +9,19 @@ module ActiveModel
       end
 
       def test_attributes_definition
-        assert_equal(['name', 'description'],
+        assert_equal([:name, :description],
                      @profile_serializer.class._attributes)
       end
 
       def test_attributes_serialization_using_serializable_hash
         assert_equal({
-          'name' => 'Name 1', 'description' => 'Description 1'
+          name: 'Name 1', description: 'Description 1'
         }, @profile_serializer.serializable_hash)
       end
 
       def test_attributes_serialization_using_as_json
         assert_equal({
-          'profile' => { 'name' => 'Name 1', 'description' => 'Description 1' }
+          'profile' => { name: 'Name 1', description: 'Description 1' }
         }, @profile_serializer.as_json)
       end
     end