public void Add_UpdatesElementInRepository(List <CounterElement> elements, int value, Guid nodeId) { elements.Add(new CounterElement(999, nodeId)); _repository.PersistValues(elements.ToImmutableHashSet()); _service.DownstreamAdd(value, nodeId); Assert.Equal(elements.Count, _repository.Elements.ToList().Count); Assert.Contains(_repository.Elements, e => e.Value == 999 + value && e.Node.Id == nodeId); }