public async Task APIShouldNotSendPrivateData()
{
// get statistics data
IActionResult data = _controller.GetAggregateData(new DateTime(2021, 03, 18), DateTime.Now);
Assert.That(data, Is.InstanceOf <OkObjectResult>());
IList <int> userIds = ((IEnumerable <Reservation>)((OkObjectResult)data).Value).Select(c => c.UserId)
.ToList();
Assert.AreEqual(1, userIds.Distinct().Count()); //Because it are all null values, distincted there should be only one item kept.
Assert.IsNull(userIds.First());
}