public void Checkin_ShouldCreateGuid()
        {
            var mockRepository = Substitute.For <ITripRepository>();
            var controller     = new TripController(mockRepository);

            var result     = controller.Checkin();
            var tripResult = Assert.IsType <TripDto>(result);

            Assert.True(Guid.TryParse(tripResult.TripIdentifier, out var _));
        }