public void AddActivityToCostsTest()
        {
            var travel = new Travel
            {
                Name = "My Travel"
            };
            var activity = new TravelActivity
            {
                Name = "My Activity"
            };

            travel.ActivityList.Add(activity);
            _repository.AddTravel(travel);
            Assert.AreEqual(1, _repository.GetTravel(travel.Id).ActivityList.Count);
            Assert.AreEqual(0, _repository.GetTravel(travel.Id).CostList.Count);
            CollectionAssert.AreEqual(travel.ActivityList as ICollection, _repository.GetTravel(travel.Id).ActivityList as ICollection);

            var cost = new MoneyValue
            {
                Value    = 24.0,
                Currency = null
            };

            _repository.AddActivityToCosts(travel.Id, activity, cost);
            Assert.AreEqual(0, _repository.GetTravel(travel.Id).ActivityList.Count);
            Assert.AreEqual(1, _repository.GetTravel(travel.Id).CostList.Count);
        }