public void RetrieveTicketScan_IdentifierNull_ThrowsArgumentNullException()
        {
            // Arrange
            var identifier = (string)null;

            // Act
            var retrieveTicketScanCall = new Action(() => _detailsViewModel.RetrieveTicketScan(identifier));

            // Assert
            Assert.That(retrieveTicketScanCall, Throws.Exception.TypeOf <ArgumentNullException>());
        }