public void AsSerializableObject_DurationIsBuilded_ObjectIsCorrectlySerialized()
        {
            Duration duration = new Duration
            {
                Days   = 1,
                Months = 2
            };
            object target = duration.AsSerializableObject();

            target.ShouldBeEquivalentTo(new
            {
                days   = 1,
                months = 2,
                weeks  = duration.Weeks
            });
        }