public async Task ShouldDeleteTrip()
{
var trip = Trips.First();
int numTrips = Trips.Count;
await TripManager.DeleteTrip(trip.Value);
Assert.That(!Trips.ContainsKey(trip.Key));
Assert.That(Trips.Count, Is.EqualTo(numTrips - 1));
var unused = Uow.Received(1).CommitAsync();
}